Rename the [Ee]xts dir to ext (#38852)

**WARNING:** This PR will probably blow up all in-flight PRs

at some point in the early days of CmdPal, two of us created seperate
`Exts` and `exts` dirs. Depending on what the casing was on the branch
that you checked one of those out from, it'd get stuck like that on your
PC forever.

Windows didn't care, so we never noticed.

But GitHub does care, and now browsing the source on GitHub is basically
impossible.

Closes #38081

src/modules/cmdpal/ext/SamplePagesExtension/Pages/SampleListPage.cs

@@ -0,0 +1,97 @@
+// 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;
+using Microsoft.CommandPalette.Extensions.Toolkit;
+
+namespace SamplePagesExtension;
+
+internal sealed partial class SampleListPage : ListPage
+{
+    public SampleListPage()
+    {
+        Icon = new IconInfo("\uEA37");
+        Name = "Sample List Page";
+    }
+
+    public override IListItem[] GetItems()
+    {
+        var confirmOnceArgs = new ConfirmationArgs
+        {
+            PrimaryCommand = new AnonymousCommand(
+                () =>
+                {
+                    var t = new ToastStatusMessage("The dialog was confirmed");
+                    t.Show();
+                })
+            {
+                Name = "Confirm",
+                Result = CommandResult.KeepOpen(),
+            },
+            Title = "You can set a title for the dialog",
+            Description = "Are you really sure you want to do the thing?",
+        };
+        var confirmTwiceArgs = new ConfirmationArgs
+        {
+            PrimaryCommand = new AnonymousCommand(() => { })
+            {
+                Name = "How sure are you?",
+                Result = CommandResult.Confirm(confirmOnceArgs),
+            },
+            Title = "You can ask twice too",
+            Description = "You probably don't want to though, that'd be annoying.",
+        };
+
+        return [
+            new ListItem(new NoOpCommand())
+            {
+                Title = "This is a basic item in the list",
+                Subtitle = "I don't do anything though",
+            },
+            new ListItem(new SampleListPageWithDetails())
+            {
+                Title = "This item will take you to another page",
+                Subtitle = "This allows for nested lists of items",
+            },
+            new ListItem(new OpenUrlCommand("https://github.com/microsoft/powertoys"))
+            {
+                Title = "Or you can go to links",
+                Subtitle = "This takes you to the PowerToys repo on GitHub",
+            },
+            new ListItem(new SampleMarkdownPage())
+            {
+                Title = "Items can have tags",
+                Subtitle = "and I'll take you to a page with markdown content",
+                Tags = [new Tag("Sample Tag")],
+            },
+            new ListItem(new SendMessageCommand())
+            {
+                Title = "I send lots of messages",
+                Subtitle = "Status messages can be used to provide feedback to the user in-app",
+            },
+            new SendSingleMessageItem(),
+            new ListItem(new IndeterminateProgressMessageCommand())
+            {
+                Title = "Do a thing with a spinner",
+                Subtitle = "Messages can have progress spinners, to indicate something is happening in the background",
+            },
+            new ListItem(
+                new AnonymousCommand(() => { })
+                {
+                    Result = CommandResult.Confirm(confirmOnceArgs),
+                })
+            {
+                Title = "Confirm before doing something",
+            },
+            new ListItem(
+                new AnonymousCommand(() => { })
+                {
+                    Result = CommandResult.Confirm(confirmTwiceArgs),
+                })
+            {
+                Title = "Confirm twice before doing something",
+            }
+        ];
+    }
+}