chore: DispatchQueueRender on Idle to prevent choking the dispatcher …

…when continuously invalidating render

src/Uno.UI/UI/Xaml/XamlRoot.crossruntime.cs

@@ -64,7 +64,7 @@ private void DispatchQueueRender()
 				_renderQueued = false;
 				InvalidateRender();
 			}
-		});
+		}, NativeDispatcherPriority.Idle);
 	}