MM-18517: Plugin Marketplace (Phase 2) (#13086)

* MM-17549: use StatusNotFound when deleting plugin (#12983)

Trying to delete a plugin that does not exist should fail with a 404, not a 400.

Relates-to: https://mattermost.atlassian.net/browse/MM-17549

* MM-19630: marketplace: model ReleaseNotesURL (#13083)

Automatic Merge

* MM-20065: allow prepackaged plugin upgrade (#13076)

* MM-20065: allow prepackaged plugin upgrade

When locally installing prepackaged plugins, skip if a plugin exists with the same id and is the same or a newer version.

This is effectively a "poor man's" rework of prepackaged plugins to allow upgrade of prepackaged plugins via the marketplace. The larger plan to rework prepackaged plugins was deferred from v5.18.

Fixes: https://mattermost.atlassian.net/browse/MM-20065

* eliminate unnecessary installPlugin

* fix TestPluginSync defaults to match minio

* cleanExistingBundles

* close prepackaged filereader

* simplify

app/plugin.go

@@ -164,10 +164,18 @@ func (a *App) InitPlugins(pluginDir, webappPluginDir string) {
 				return nil
 			}
 
-			if fileReader, err := os.Open(walkPath); err != nil {
+			fileReader, err := os.Open(walkPath)
+			if err != nil {
 				mlog.Error("Failed to open prepackaged plugin", mlog.Err(err), mlog.String("path", walkPath))
-			} else if _, err := a.installPluginLocally(fileReader, true); err != nil {
-				mlog.Error("Failed to unpack prepackaged plugin", mlog.Err(err), mlog.String("path", walkPath))
+				return nil
+			}
+			defer fileReader.Close()
+
+			mlog.Debug("Installing prepackaged plugin", mlog.String("path", walkPath))
+
+			_, appErr := a.installPluginLocally(fileReader, installPluginLocallyOnlyIfNewOrUpgrade)
+			if appErr != nil {
+				mlog.Error("Failed to unpack prepackaged plugin", mlog.Err(appErr), mlog.String("path", walkPath))
 			}
 
 			return nil
@@ -250,7 +258,7 @@ func (a *App) SyncPlugins() *model.AppError {
 		defer reader.Close()
 
 		mlog.Info("Syncing plugin from file store", mlog.String("bundle", path))
-		if _, err := a.installPluginLocally(reader, true); err != nil {
+		if _, err := a.installPluginLocally(reader, installPluginLocallyAlways); err != nil {
 			mlog.Error("Failed to sync plugin from file store", mlog.String("bundle", path), mlog.Err(err))
 		}
 	}
@@ -364,7 +372,7 @@ func (a *App) DisablePlugin(id string) *model.AppError {
 	}
 
 	if manifest == nil {
-		return model.NewAppError("DisablePlugin", "app.plugin.not_installed.app_error", nil, "", http.StatusBadRequest)
+		return model.NewAppError("DisablePlugin", "app.plugin.not_installed.app_error", nil, "", http.StatusNotFound)
 	}
 
 	a.UpdateConfig(func(cfg *model.Config) {