[MacCatalyst] Get correct window associated with the Popup (#1409)

* Get correct window associated with the Popup

* Update src/CommunityToolkit.Maui.Core/Views/Popup/MauiPopup.macios.cs

Co-authored-by: Pedro Jesus <pedrojesus.cefet@gmail.com>

* Use PageHandler to get the native UIViewController.

Use PageHandler to get native UIViewController associated with the popup.

* Nit: Removed explicitly declared ‘rootViewController’ variable and merged it with the variable assignment.

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Co-authored-by: vbabenko <vitaliy.babenko@idx.us>
Co-authored-by: Pedro Jesus <pedrojesus.cefet@gmail.com>

src/CommunityToolkit.Maui.Core/Views/Popup/MauiPopup.macios.cs

@@ -95,7 +95,8 @@ public void SetElement(IPopup element)
 		_ = View ?? throw new InvalidOperationException($"{nameof(View)} cannot be null.");
 		_ = VirtualView ?? throw new InvalidOperationException($"{nameof(VirtualView)} cannot be null.");
 
-		var rootViewController = WindowStateManager.Default.GetCurrentUIViewController() ?? throw new InvalidOperationException($"{nameof(PageHandler.ViewController)} cannot be null.");
+		var pagehandler = VirtualView.Parent.Handler as PageHandler;
+		var rootViewController = pagehandler?.ViewController ?? WindowStateManager.Default.GetCurrentUIViewController() ?? throw new InvalidOperationException($"{nameof(PageHandler.ViewController)} cannot be null.");
 		ViewController ??= rootViewController;
 		SetDimmingBackgroundEffect();
 	}