PLT-3105 Files table migration (#4068)

* Implemented initial changes for files table

* Removed *_benchmark_test.go files

* Re-implemented GetPublicFile and added support for old path

* Localization for files table

* Moved file system code into utils package

* Finished server-side changes and added initial upgrade script

* Added getPostFiles api

* Re-add Extension and HasPreviewImage fields to FileInfo

* Removed unused translation

* Fixed merge conflicts left over after permissions changes

* Forced FileInfo.extension to be lower case

* Changed FileUploadResponse to contain the FileInfos instead of FileIds

* Fixed permissions on getFile* calls

* Fixed notifications for file uploads

* Added initial version of client code for files changes

* Permanently added FileIds field to Post object and removed Post.HasFiles

* Updated PostStore.Update to be usable in more circumstances

* Re-added Filenames field and switched file migration to be entirely lazy-loaded

* Increased max listener count for FileStore

* Removed unused fileInfoCache

* Moved file system code back into api

* Removed duplicate test case

* Fixed unit test running on ports other than 8065

* Renamed HasPermissionToPostContext to HasPermissionToChannelByPostContext

* Refactored handleImages to make it more easily understandable

* Renamed getPostFiles to getFileInfosForPost

* Re-added pre-FileIds posts to analytics

* Changed files to be saved as their ids as opposed to id/filename.ext

* Renamed FileInfo.UserId to FileInfo.CreatorId

* Fixed detection of language in CodePreview

* Fixed switching between threads in the RHS not loading new files

* Add serverside protection against a rare bug where the client sends the same file twice for a single post

* Refactored the important parts of uploadFile api call into a function that can be called without a web context

i18n/en.json

@@ -829,14 +829,6 @@
     "id": "api.emoji.upload.large_image.app_error",
     "translation": "Unable to create emoji. Image must be at most 128 by 128 pixels."
   },
-  {
-    "id": "api.file.file_upload.exceeds",
-    "translation": "File exceeds max image size."
-  },
-  {
-    "id": "api.file.get_file.not_found.app_error",
-    "translation": "Could not find file."
-  },
   {
     "id": "api.file.get_file.public_disabled.app_error",
     "translation": "Public links have been disabled by the system administrator"
@@ -849,30 +841,98 @@
     "id": "api.file.get_public_link.disabled.app_error",
     "translation": "Public links have been disabled"
   },
+  {
+    "id": "api.file.get_public_link.no_post.app_error",
+    "translation": "Unable to get public link for file. File must be attached to a post that can be read by the current user."
+  },
+  {
+    "id": "api.file.get_file_preview.no_thumbnail.app_error",
+    "translation": "File doesn't have a preview image"
+  },
+  {
+    "id": "api.file.get_file_thumbnail.no_thumbnail.app_error",
+    "translation": "File doesn't have a thumbnail image"
+  },
+  {
+    "id": "api.file.get_public_file_old.storage.app_error",
+    "translation": "Unable to get file. Image storage is not configured."
+  },
+  {
+    "id": "api.file.get_public_file_old.storage.app_error",
+    "translation": "Unable to get file. Image storage is not configured."
+  },
+  {
+    "id": "api.file.get_info_for_request.no_post.app_error",
+    "translation": "Unable to get info for file. File must be attached to a post that can be read by the current user."
+  },
+  {
+    "id": "api.file.get_info_for_request.storage.app_error",
+    "translation": "Unable to get info for file. Image storage is not configured."
+  },
   {
     "id": "api.file.handle_images_forget.decode.error",
-    "translation": "Unable to decode image channelId=%v userId=%v filename=%v err=%v"
+    "translation": "Unable to decode image err=%v"
   },
   {
     "id": "api.file.handle_images_forget.encode_jpeg.error",
-    "translation": "Unable to encode image as jpeg channelId=%v userId=%v filename=%v err=%v"
+    "translation": "Unable to encode image as jpeg path=%v err=%v"
   },
   {
     "id": "api.file.handle_images_forget.encode_preview.error",
-    "translation": "Unable to encode image as preview jpg channelId=%v userId=%v filename=%v err=%v"
+    "translation": "Unable to encode image as preview jpg path=%v err=%v"
   },
   {
     "id": "api.file.handle_images_forget.upload_preview.error",
-    "translation": "Unable to upload preview channelId=%v userId=%v filename=%v err=%v"
+    "translation": "Unable to upload preview path=%v err=%v"
   },
   {
     "id": "api.file.handle_images_forget.upload_thumb.error",
-    "translation": "Unable to upload thumbnail channelId=%v userId=%v filename=%v err=%v"
+    "translation": "Unable to upload thumbnail path=%v err=%v"
   },
   {
     "id": "api.file.init.debug",
     "translation": "Initializing file api routes"
   },
+  {
+    "id": "api.file.migrate_filenames_to_file_infos.channel.app_error",
+    "translation": "Unable to get channel when migrating post to use FileInfos, post_id=%v, channel_id=%v, err=%v"
+  },
+  {
+    "id": "api.file.migrate_filenames_to_file_infos.file_not_found.warn",
+    "translation": "Unable to find file when migrating post to use FileInfos, post_id=%v, filename=%v, path=%v, err=%v"
+  },
+  {
+    "id": "api.file.migrate_filenames_to_file_infos.info.app_error",
+    "translation": "Unable to fully decode file info when migrating post to use FileInfos, post_id=%v, filename=%v, err=%v"
+  },
+  {
+    "id": "api.file.migrate_filenames_to_file_infos.mismatched_filename.warn",
+    "translation": "Found an unusual filename when migrating post to use FileInfos, post_id=%v, channel_id=%v, user_id=%v, filename=%v"
+  },
+  {
+    "id": "api.file.migrate_filenames_to_file_infos.no_filenames.warn",
+    "translation": "Unable to migrate post to use FileInfos with an empty Filenames field, post_id=%v"
+  },
+  {
+    "id": "api.file.migrate_filenames_to_file_infos.save_file_info.warn",
+    "translation": "Unable to save post when migrating post to use FileInfos, post_id=%v, new_file_ids=%v, old_filenames=%v, err=%v"
+  },
+  {
+    "id": "api.file.migrate_filenames_to_file_infos.save_post.warn",
+    "translation": "Unable to save file info when migrating post to use FileInfos, post_id=%v, file_id=%v, filename=%v, err=%v"
+  },
+  {
+    "id": "api.file.migrate_filenames_to_file_infos.team_id.app_error",
+    "translation": "Unable to find team for FileInfos, post_id=%v, filenames=%v"
+  },
+  {
+    "id": "api.file.migrate_filenames_to_file_infos.teams.app_error",
+    "translation": "Unable to get teams when migrating post to use FileInfos, post_id=%v, err=%v"
+  },
+  {
+    "id": "api.file.migrate_filenames_to_file_infos.unexpected_filename.error",
+    "translation": "Unable to decipher filename when migrating post to use FileInfos, post_id=%v, filename=%v"
+  },
   {
     "id": "api.file.move_file.configured.app_error",
     "translation": "File storage not configured properly. Please configure for either S3 or local server file storage."
@@ -917,22 +977,6 @@
     "id": "api.file.read_file.reading_local.app_error",
     "translation": "Encountered an error reading from local server storage"
   },
-  {
-    "id": "api.file.upload_file.image.app_error",
-    "translation": "Unable to upload image file."
-  },
-  {
-    "id": "api.file.upload_file.large_image.app_error",
-    "translation": "Unable to upload image file. File is too large."
-  },
-  {
-    "id": "api.file.upload_file.storage.app_error",
-    "translation": "Unable to upload file. Image storage is not configured."
-  },
-  {
-    "id": "api.file.upload_file.too_large.app_error",
-    "translation": "Unable to upload file. File is too large."
-  },
   {
     "id": "api.file.write_file.configured.app_error",
     "translation": "File storage not configured properly. Please configure for either S3 or local server file storage."
@@ -949,6 +993,18 @@
     "id": "api.file.write_file_locally.writing.app_error",
     "translation": "Encountered an error writing to local server storage"
   },
+  {
+    "id": "api.file.upload_file.large_image.app_error",
+    "translation": "Unable to upload image file. File is too large."
+  },
+  {
+    "id": "api.file.upload_file.storage.app_error",
+    "translation": "Unable to upload file. Image storage is not configured."
+  },
+  {
+    "id": "api.file.upload_file.too_large.app_error",
+    "translation": "Unable to upload file. File is too large."
+  },
   {
     "id": "api.general.init.debug",
     "translation": "Initializing general api routes"
@@ -1161,6 +1217,10 @@
     "id": "api.post.check_for_out_of_channel_mentions.message.one",
     "translation": "{{.Username}} was mentioned, but they did not receive a notification because they do not belong to this channel."
   },
+  {
+    "id": "api.post.create_post.attach_files.error",
+    "translation": "Encountered error attaching files to post, post_id=%s, user_id=%s, file_ids=%v, err=%v"
+  },
   {
     "id": "api.post.create_post.bad_filename.error",
     "translation": "Bad filename discarded, filename=%v"
@@ -1197,6 +1257,14 @@
     "id": "api.post.delete_post.permissions.app_error",
     "translation": "You do not have the appropriate permissions"
   },
+  {
+    "id": "api.post.delete_post_files.app_error.warn",
+    "translation": "Encountered error when deleting files for post, post_id=%v, err=%v"
+  },
+  {
+    "id": "api.post.get_message_for_notification.get_files.error",
+    "translation": "Encountered error when getting files for notification message, post_id=%v, err=%v"
+  },
   {
     "id": "api.post.get_message_for_notification.files_sent",
     "translation": {
@@ -1287,6 +1355,10 @@
     "id": "api.post.send_notifications_and_forget.comment_thread.error",
     "translation": "Failed to retrieve comment thread posts in notifications root_post_id=%v, err=%v"
   },
+  {
+    "id": "api.post.send_notifications_and_forget.files.error",
+    "translation": "Failed to get files for post notification post_id=%v, err=%v"
+  },
   {
     "id": "api.post.send_notifications_and_forget.get_teams.error",
     "translation": "Failed to get teams when sending cross-team DM user_id=%v, err=%v"
@@ -3423,6 +3495,10 @@
     "id": "model.post.is_valid.filenames.app_error",
     "translation": "Invalid filenames"
   },
+  {
+    "id": "model.post.is_valid.file_ids.app_error",
+    "translation": "Invalid file ids"
+  },
   {
     "id": "model.post.is_valid.hashtags.app_error",
     "translation": "Invalid hashtags"
@@ -3875,6 +3951,10 @@
     "id": "store.sql_channel.get_extra_members.app_error",
     "translation": "We couldn't get the extra info for channel members"
   },
+  {
+    "id": "store.sql_channel.get_for_post.app_error",
+    "translation": "We couldn't get the channel for the given post"
+  },
   {
     "id": "store.sql_channel.get_member.app_error",
     "translation": "We couldn't get the channel member"
@@ -3887,6 +3967,10 @@
     "id": "store.sql_channel.get_member_count.app_error",
     "translation": "We couldn't get the channel member count"
   },
+  {
+    "id": "store.sql_channel.get_member_for_post.app_error",
+    "translation": "We couldn't get the channel member for the given post"
+  },
   {
     "id": "store.sql_channel.get_members.app_error",
     "translation": "We couldn't get the channel members"
@@ -4071,6 +4155,30 @@
     "id": "store.sql_emoji.save.app_error",
     "translation": "We couldn't save the emoji"
   },
+  {
+    "id": "store.sql_file_info.attach_to_post.app_error",
+    "translation": "We couldn't attach the file info to the post"
+  },
+  {
+    "id": "store.sql_file_info.delete_for_post.app_error",
+    "translation": "We couldn't delete the file info to the post"
+  },
+  {
+    "id": "store.sql_file_info.get.app_error",
+    "translation": "We couldn't get the file info"
+  },
+  {
+    "id": "store.sql_file_info.get_by_path.app_error",
+    "translation": "We couldn't get the file info by path"
+  },
+  {
+    "id": "store.sql_file_info.get_for_post.app_error",
+    "translation": "We couldn't get the file info for the post"
+  },
+  {
+    "id": "store.sql_file_info.save.app_error",
+    "translation": "We couldn't save the file info"
+  },
   {
     "id": "store.sql_license.get.app_error",
     "translation": "We encountered an error getting the license"