WindowServer: Don't spam clients with resize events.

Wait for them to finish a paint, then send them a new resize event.
The exception is when releasing the mouse button to end the resize.
Then we send a new resize event right away.

WindowServer/WSClientConnection.cpp

@@ -358,6 +358,7 @@ void WSClientConnection::handle_request(WSAPIDidFinishPaintingNotification& requ
         return;
     }
     auto& window = *(*it).value;
+    window.set_has_painted_since_last_resize(true);
     WSWindowManager::the().invalidate(window, request.rect());
 }