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>

manualtesting/manual_testing.go

@@ -94,7 +94,7 @@ func manualTest(c *web.Context, w http.ResponseWriter, r *http.Request) {
 		}
 
 		channel := &model.Channel{DisplayName: "Town Square", Name: "town-square", Type: model.CHANNEL_OPEN, TeamId: createdTeam.Id}
-		if _, err := c.App.CreateChannel(channel, false); err != nil {
+		if _, err := c.App.CreateChannel(c.AppContext, channel, false); err != nil {
 			c.Err = err
 			return
 		}