QSystemTrayIcon::messageClicked also invoked if clicked on foreign notifications

Originally reported as https://github.com/keshavbhatt/whatsie/issues/42.

The application uses a QSystemTrayIcon. Whenever the tray icon or message is clicked, the application window opens in the foreground.

The bug is that even if any other application (mail client, browser) shows a notification, the Qt application opens itself in the foreground. This is highly annoying.

The cause for this is that QDBusTray connects to the ActionInvoked Signal without checking that it was invoked for the notification sent by this application.