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/SampleUpdatingItemsPage.cs

@@ -0,0 +1,43 @@
+// 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 System.Timers;
+using Microsoft.CommandPalette.Extensions;
+using Microsoft.CommandPalette.Extensions.Toolkit;
+using Microsoft.VisualBasic;
+
+namespace SamplePagesExtension;
+
+public partial class SampleUpdatingItemsPage : ListPage
+{
+    private readonly ListItem hourItem = new(new NoOpCommand());
+    private readonly ListItem minuteItem = new(new NoOpCommand());
+    private readonly ListItem secondItem = new(new NoOpCommand());
+    private static Timer timer;
+
+    public SampleUpdatingItemsPage()
+    {
+        Name = "Open";
+        Icon = new IconInfo("\uE72C");
+    }
+
+    public override IListItem[] GetItems()
+    {
+        if (timer == null)
+        {
+            timer = new Timer(500);
+            timer.Elapsed += (object source, ElapsedEventArgs e) =>
+            {
+                var current = DateAndTime.Now;
+                hourItem.Title = $"{current.Hour}";
+                minuteItem.Title = $"{current.Minute}";
+                secondItem.Title = $"{current.Second}";
+            };
+            timer.AutoReset = true; // Keep repeating
+            timer.Enabled = true;
+        }
+
+        return [hourItem, minuteItem, secondItem];
+    }
+}