Adds logical deletes to shared channel remotes and remote clusters (#28159)

* Adds logical deletes to shared channel remotes and remote clusters

Instead of physically deleting the shared channel remote and remote
clusters records when a channel is unshared, a remote uninvited or a
remote cluster is deleted, now those have a logical `DeleteAt` field
that is set.

This allows us to safely restore shared channels between two remote
clusters (as of now resetting the cursor without backfilling their
contents) and to know which connections were established in the past
and now are severed.

* Delete the index in remoteclusters before adding the new column

* Fix bad error check

server/i18n/en.json

@@ -1339,7 +1339,7 @@
   },
   {
     "id": "api.command_remote.remote_table_header",
-    "translation": "| Secure connection | Display name | Connection ID | Site URL | Invite accepted | Online | Last ping  |"
+    "translation": "| Secure connection | Display name | Connection ID | Site URL | Default Team | Invite accepted | Online | Last ping | Deleted |"
   },
   {
     "id": "api.command_remote.remotes_not_found",
@@ -3758,6 +3758,10 @@
     "id": "api.upgrade_to_enterprise_status.signature.app_error",
     "translation": "Mattermost was unable to upgrade to Enterprise Edition. The digital signature of the downloaded binary file could not be verified."
   },
+  {
+    "id": "api.upload.create.upload_channel_not_shared_with_remote.app_error",
+    "translation": "Failed to upload file. Upload channel is not shared with remote."
+  },
   {
     "id": "api.upload.create.upload_too_large.app_error",
     "translation": "Unable to upload file. File is too large."