fix(NativeApplication): don't call OnLaunched again if app is already…

… running (i.e. when focus is regained)

src/Uno.UI/UI/Xaml/NativeApplication.cs

@@ -74,7 +74,7 @@ private void OnActivityStarted(Activity activity)
 				}
 
 				// default to normal launch
-				if (!handled)
+				if (!handled && !_isRunning)
 				{
 					_app.OnLaunched(new LaunchActivatedEventArgs());
 				}