UI: Properly ensure save on exit

I broke the save that happens on exit by making all project saves put on
the message queue.  The save on exit would put the save on to the
message queue, then by the time the save occurred obs would already be
shut down.

This just calls the save function directly rather than deferring it to
the message queue.

obs/window-basic-main.cpp

@@ -2199,7 +2199,8 @@ void OBSBasic::closeEvent(QCloseEvent *event)
 	// the destructor gets called
 	obs_remove_draw_callback(OBSBasic::RenderMain, this);
 
-	SaveProject();
+	projectChanged = true;
+	SaveProjectDeferred();
 	disableSaving++;
 
 	/* Clear all scene data (dialogs, widgets, widget sub-items, scenes,