Standardizing built-in extension icon handling (#40606)

Just standardizing built-in extensions to use a `internal sealed class
Icons` for all their non-dynamic icons.

Looks like a LOT of changes, but it's icons all the way down.

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WindowWalker/Commands/CloseWindowCommand.cs

@@ -20,7 +20,7 @@ internal sealed partial class CloseWindowCommand : InvokableCommand
 
     public CloseWindowCommand(Window window)
     {
-        Icon = new IconInfo("\uE894");
+        Icon = Icons.CloseWindow;
         Name = $"{Resources.windowwalker_Close}";
         _window = window;
     }

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WindowWalker/Commands/EndTaskCommand.cs

@@ -21,7 +21,7 @@ internal sealed partial class EndTaskCommand : InvokableCommand
 
     public EndTaskCommand(Window window)
     {
-        Icon = new IconInfo("\uF140");
+        Icon = Icons.EndTask;
         Name = $"{Resources.windowwalker_Kill}";
         _window = window;
     }

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WindowWalker/Components/ResultHelper.cs

@@ -119,7 +119,7 @@ internal static class ResultHelper
         return new WindowWalkerListItem(null)
         {
             Title = Resources.windowwalker_ExplorerInfoTitle,
-            Icon = new IconInfo("\uE946"), // Info
+            Icon = Icons.Info,
             Subtitle = Resources.windowwalker_ExplorerInfoSubTitle,
             Command = new ExplorerInfoResultCommand(),
         };

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WindowWalker/Icons.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Microsoft.CommandPalette.Extensions.Toolkit;
+
+namespace Microsoft.CmdPal.Ext.WindowWalker;
+
+internal sealed class Icons
+{
+    internal static IconInfo WindowWalkerIcon { get; } = IconHelpers.FromRelativePath("Assets\\WindowWalker.svg");
+
+    internal static IconInfo EndTask { get; } = new IconInfo("\uF140"); // StatusCircleBlock
+
+    internal static IconInfo CloseWindow { get; } = new IconInfo("\uE894"); // Clear
+
+    internal static IconInfo Info { get; } = new IconInfo("\uE946"); // Info
+}

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WindowWalker/Pages/WindowWalkerListPage.cs

@@ -19,7 +19,7 @@ internal sealed partial class WindowWalkerListPage : DynamicListPage, IDisposabl
 
     public WindowWalkerListPage()
     {
-        Icon = IconHelpers.FromRelativePath("Assets\\WindowWalker.svg");
+        Icon = Icons.WindowWalkerIcon;
         Name = Resources.windowwalker_name;
         Id = "com.microsoft.cmdpal.windowwalker";
         PlaceholderText = Resources.windowwalker_PlaceholderText;

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WindowWalker/WindowWalkerCommandsProvider.cs

@@ -20,7 +20,7 @@ public partial class WindowWalkerCommandsProvider : CommandProvider
     {
         Id = "WindowWalker";
         DisplayName = Resources.windowwalker_name;
-        Icon = IconHelpers.FromRelativePath("Assets\\WindowWalker.svg");
+        Icon = Icons.WindowWalkerIcon;
         Settings = SettingsManager.Instance.Settings;
 
         _windowWalkerPageItem = new CommandItem(new WindowWalkerListPage())