Call closeProject before quit to ensure a clean shutdown

ApplicationLibCode/Commands/ApplicationCommands/RicExitApplicationFeature.cpp

@@ -66,6 +66,7 @@ void RicExitApplicationFeature::onActionTriggered( bool isChecked )
     // This was required after moving to Qt6, causing the application not to shut down properly, and ghost processes remains after a forced
     // shutdown. The slot onLastWindowClosed() configured in RiaGuiApplication::RiaGuiApplication is never called. Testing with
     // processEvents() had no effect.
+    app->closeProject();
     app->quit();
 }