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/session_test.go

@@ -148,7 +148,7 @@ func TestUpdateSessionOnPromoteDemote(t *testing.T) {
 		require.Nil(t, err)
 		assert.Equal(t, "true", rsession.Props[model.SESSION_PROP_IS_GUEST])
 
-		err = th.App.PromoteGuestToUser(guest, th.BasicUser.Id)
+		err = th.App.PromoteGuestToUser(th.Context, guest, th.BasicUser.Id)
 		require.Nil(t, err)
 
 		rsession, err = th.App.GetSession(session.Token)