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.ViewModels/CommandProviderWrapper.cs

@@ -6,6 +6,8 @@ using ManagedCommon;
 using Microsoft.CmdPal.Common.Services;
 using Microsoft.CmdPal.UI.ViewModels.Models;
 using Microsoft.CommandPalette.Extensions;
+using Microsoft.Extensions.DependencyInjection;
+
 using Windows.Foundation;
 
 namespace Microsoft.CmdPal.UI.ViewModels;
@@ -20,9 +22,9 @@ public sealed class CommandProviderWrapper
 
     private readonly TaskScheduler _taskScheduler;
 
-    public ICommandItem[] TopLevelItems { get; private set; } = [];
+    public TopLevelViewModel[] TopLevelItems { get; private set; } = [];
 
-    public IFallbackCommandItem[] FallbackItems { get; private set; } = [];
+    public TopLevelViewModel[] FallbackItems { get; private set; } = [];
 
     public string DisplayName { get; private set; } = string.Empty;
 
@@ -38,7 +40,13 @@ public sealed class CommandProviderWrapper
 
     public CommandSettingsViewModel? Settings { get; private set; }
 
-    public string ProviderId => $"{Extension?.PackageFamilyName ?? string.Empty}/{Id}";
+    public string ProviderId
+    {
+        get
+        {
+            return string.IsNullOrEmpty(Extension?.ExtensionUniqueId) ? Id : Extension.ExtensionUniqueId;
+        }
+    }
 
     public CommandProviderWrapper(ICommandProvider provider, TaskScheduler mainThread)
     {
@@ -105,13 +113,25 @@ public sealed class CommandProviderWrapper
         isValid = true;
     }
 
-    public async Task LoadTopLevelCommands()
+    private ProviderSettings GetProviderSettings(SettingsModel settings)
+    {
+        return settings.GetProviderSettings(this);
+    }
+
+    public async Task LoadTopLevelCommands(IServiceProvider serviceProvider, WeakReference<IPageContext> pageContext)
     {
         if (!isValid)
         {
             return;
         }
 
+        var settings = serviceProvider.GetService<SettingsModel>()!;
+
+        if (!GetProviderSettings(settings).IsEnabled)
+        {
+            return;
+        }
+
         ICommandItem[]? commands = null;
         IFallbackCommandItem[]? fallbacks = null;
 
@@ -119,7 +139,7 @@ public sealed class CommandProviderWrapper
         {
             var model = _commandProvider.Unsafe!;
 
-            var t = new Task<ICommandItem[]>(model.TopLevelCommands);
+            Task<ICommandItem[]> t = new(model.TopLevelCommands);
             t.Start();
             commands = await t.ConfigureAwait(false);
 
@@ -134,6 +154,8 @@ public sealed class CommandProviderWrapper
             Settings = new(model.Settings, this, _taskScheduler);
             Settings.InitializeProperties();
 
+            InitializeCommands(commands, fallbacks, serviceProvider, pageContext);
+
             Logger.LogDebug($"Loaded commands from {DisplayName} ({ProviderId})");
         }
         catch (Exception e)
@@ -142,15 +164,33 @@ public sealed class CommandProviderWrapper
             Logger.LogError($"Extension was {Extension!.PackageFamilyName}");
             Logger.LogError(e.ToString());
         }
+    }
 
+    private void InitializeCommands(ICommandItem[] commands, IFallbackCommandItem[] fallbacks, IServiceProvider serviceProvider, WeakReference<IPageContext> pageContext)
+    {
+        var settings = serviceProvider.GetService<SettingsModel>()!;
+
+        Func<ICommandItem?, bool, TopLevelViewModel> makeAndAdd = (ICommandItem? i, bool fallback) =>
+        {
+            CommandItemViewModel commandItemViewModel = new(new(i), pageContext);
+            TopLevelViewModel topLevelViewModel = new(commandItemViewModel, fallback, ExtensionHost, ProviderId, settings, serviceProvider);
+
+            topLevelViewModel.ItemViewModel.SlowInitializeProperties();
+
+            return topLevelViewModel;
+        };
         if (commands != null)
         {
-            TopLevelItems = commands;
+            TopLevelItems = commands
+                .Select(c => makeAndAdd(c, false))
+                .ToArray();
         }
 
         if (fallbacks != null)
         {
-            FallbackItems = fallbacks;
+            FallbackItems = fallbacks
+                .Select(c => makeAndAdd(c, true))
+                .ToArray();
         }
     }