Remove AttachDevToolsToTopLevelOnVisualTreeAttachment since @grokys doesn't like it

samples/interop/WindowsInteropTest/EmbedToWpfDemo.xaml.cs

@@ -13,6 +13,7 @@ using System.Windows.Navigation;
 using System.Windows.Shapes;
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.VisualTree;
 using ControlCatalog;
 using Window = System.Windows.Window;
 
@@ -27,8 +28,10 @@ namespace WindowsInteropTest
         {
             InitializeComponent();
             var view = new MainView();
-            
-            view.AttachDevToolsToTopLevelOnVisualTreeAttachment();
+            view.AttachedToVisualTree += delegate
+            {
+                ((TopLevel) view.GetVisualRoot()).AttachDevTools(); 
+            };
             Host.Content = view;
             var btn = (Avalonia.Controls.Button) RightBtn.Content;
             btn.Click += delegate

src/Avalonia.Diagnostics/DevTools.xaml.cs

@@ -20,15 +20,6 @@ namespace Avalonia
 		{
 			Avalonia.Diagnostics.DevTools.Attach(control);
 		}
-
-	    public static void AttachDevToolsToTopLevelOnVisualTreeAttachment(this Control control)
-	    {
-	        (control.GetVisualRoot() as TopLevel)?.AttachDevTools();
-            control.AttachedToVisualTree += delegate
-	        {
-                (control.GetVisualRoot() as TopLevel)?.AttachDevTools();
-	        };
-	    }
 	}
 }