Migrate to stateless app.App (#17542)

* add request context

* move initialialization to server

* use app interface instead of global app functions

* remove app context from webconn

* cleanup

* remove duplicated services

* move context to separate package

* remove finalize init method and move content to NewServer function

* restart workers and schedulers after adding license for tests

* reflect review comments

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

app/plugin_event.go

@@ -7,10 +7,9 @@ import (
 	"github.com/mattermost/mattermost-server/v5/model"
 )
 
-// notifyClusterPluginEvent publishes `event` to other clusters.
-func (a *App) notifyClusterPluginEvent(event string, data model.PluginEventData) {
-	if a.Cluster() != nil {
-		a.Cluster().SendClusterMessage(&model.ClusterMessage{
+func (s *Server) notifyClusterPluginEvent(event string, data model.PluginEventData) {
+	if s.Cluster != nil {
+		s.Cluster.SendClusterMessage(&model.ClusterMessage{
 			Event:            event,
 			SendType:         model.CLUSTER_SEND_RELIABLE,
 			WaitForAllToSend: true,