CmdPal: Fix SUI crash ; Allow extensions to be disabled (#38040)

Both `TopLevelCommandItemWrapper` and `TopLevelViewModel` were really the same thing. The latter was from an earlier prototype, and the former is a more correct, safer abstraction. We really should have only ever used the former, but alas, we only used it for the SUI, and it piggy-backed off the latter, and that meant the latter's bugs became the former's.


tldr: I made the icon access safe in the SUI. 

And while I was doing this, because we now have a cleaner VM abstraction here in the host, we can actually cleanly disable extensions, because the `CommandProviderWrapper` knows which `ViewModel`s it made. 

Closes https://github.com/zadjii-msft/PowerToys/issues/426
Closes https://github.com/zadjii-msft/PowerToys/issues/478
Closes https://github.com/zadjii-msft/PowerToys/issues/577

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/ContentIcon.cs

@@ -2,13 +2,11 @@
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Runtime.InteropServices;
 using CommunityToolkit.WinUI;
-using Microsoft.CmdPal.UI.Deferred;
-using Microsoft.CmdPal.UI.ViewModels;
-using Microsoft.UI.Dispatching;
+using ManagedCommon;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
-using Windows.Foundation;
 
 namespace Microsoft.CmdPal.UI.Controls;
 
@@ -39,7 +37,14 @@ public partial class ContentIcon : FontIcon
     {
         if (this.FindDescendants().OfType<Grid>().FirstOrDefault() is Grid grid && Content is not null)
         {
-            grid.Children.Add(Content);
+            try
+            {
+                grid.Children.Add(Content);
+            }
+            catch (COMException ex)
+            {
+                Logger.LogError(ex.ToString());
+            }
         }
     }
 }