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/post_metadata.go

@@ -36,9 +36,9 @@ var linkCache = cache.NewLRU(cache.LRUOptions{
 	Size: LinkCacheSize,
 })
 
-func (a *App) InitPostMetadata() {
+func (s *Server) initPostMetadata() {
 	// Dump any cached links if the proxy settings have changed so image URLs can be updated
-	a.AddConfigListener(func(before, after *model.Config) {
+	s.AddConfigListener(func(before, after *model.Config) {
 		if (before.ImageProxySettings.Enable != after.ImageProxySettings.Enable) ||
 			(before.ImageProxySettings.ImageProxyType != after.ImageProxySettings.ImageProxyType) ||
 			(before.ImageProxySettings.RemoteImageProxyURL != after.ImageProxySettings.RemoteImageProxyURL) ||