fix: Avoid propagating routed events up from PopupPanel

In case of UWP and WinUI, routed events are not propagated up from Popups, even if they are part of the visual tree and their Parent is set. Because we currently override the logical parent on Android and iOS by overwriting the actual parent, the only way to stop the propagation is to actually stop it at the PopupPanel level.

(cherry picked from commit 326a0ec)

src/Uno.UI/UI/Xaml/UIElement.RoutedEvents.cs

@@ -16,6 +16,8 @@
 using Uno.UI.Xaml.Input;
 using Windows.Foundation;
 using Windows.UI.Xaml.Input;
+using Uno.UI.Xaml.Core;
+using Windows.UI.Xaml.Controls.Primitives;
 
 #if __IOS__
 using UIKit;
@@ -719,15 +721,20 @@ internal bool RaiseEvent(RoutedEvent routedEvent, RoutedEventArgs args, Bubbling
 				args.CanBubbleNatively = false;
 			}
 
-			var parent = this.GetParent() as UIElement;
+			UIElement parent = null;
+			if (this is not PopupPanel)
+			{
+				parent = this.GetParent() as UIElement;
+
 #if __IOS__ || __ANDROID__
-			// This is for safety (legacy support) and should be removed.
-			// A common issue is the managed parent being cleared before unload event raised.
-			parent ??= this.FindFirstParent<UIElement>();
+				// This is for safety (legacy support) and should be removed.
+				// A common issue is the managed parent being cleared before unload event raised.
+				parent ??= this.FindFirstParent<UIElement>();
 #endif
+			}
 
 			// [11] A parent is defined?
-			if (parent == null)
+			if (parent is null)
 			{
 				return isHandled; // [12] processing finished
 			}