[MM-26812] Add support for resumable file uploads (#15252)

* Implement AppendFile for FileBackend

* Split test into subtests

* [MM-26812] Add support for resumable file uploads (#15252)

* Implement UploadSession

* Implement UploadSessionStore

* Add error strings

* Implement resumable file uploads

* Add UploadType

* Fix retry layer tests

* Regenerate store layers

* Fix store error handling

* Use base for filename

* Prevent concurrent uploads on the same upload session

* Fix erroneus error string

* Improve error handling

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

* Fix translations

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/api.go

@@ -57,6 +57,9 @@ type Routes struct {
 	Files *mux.Router // 'api/v4/files'
 	File  *mux.Router // 'api/v4/files/{file_id:[A-Za-z0-9]+}'
 
+	Uploads *mux.Router // 'api/v4/uploads'
+	Upload  *mux.Router // 'api/v4/uploads/{upload_id:[A-Za-z0-9]+}'
+
 	Plugins *mux.Router // 'api/v4/plugins'
 	Plugin  *mux.Router // 'api/v4/plugins/{plugin_id:[A-Za-z0-9\\_\\-\\.]+}'
 
@@ -173,6 +176,9 @@ func Init(configservice configservice.ConfigService, globalOptionsFunc app.AppOp
 	api.BaseRoutes.File = api.BaseRoutes.Files.PathPrefix("/{file_id:[A-Za-z0-9]+}").Subrouter()
 	api.BaseRoutes.PublicFile = api.BaseRoutes.Root.PathPrefix("/files/{file_id:[A-Za-z0-9]+}/public").Subrouter()
 
+	api.BaseRoutes.Uploads = api.BaseRoutes.ApiRoot.PathPrefix("/uploads").Subrouter()
+	api.BaseRoutes.Upload = api.BaseRoutes.Uploads.PathPrefix("/{upload_id:[A-Za-z0-9]+}").Subrouter()
+
 	api.BaseRoutes.Plugins = api.BaseRoutes.ApiRoot.PathPrefix("/plugins").Subrouter()
 	api.BaseRoutes.Plugin = api.BaseRoutes.Plugins.PathPrefix("/{plugin_id:[A-Za-z0-9\\_\\-\\.]+}").Subrouter()
 
@@ -227,6 +233,7 @@ func Init(configservice configservice.ConfigService, globalOptionsFunc app.AppOp
 	api.InitChannel()
 	api.InitPost()
 	api.InitFile()
+	api.InitUpload()
 	api.InitSystem()
 	api.InitLicense()
 	api.InitConfig()