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/Microsoft.CmdPal.Ext.Apps/Utils/ShellLocalization.cs

@@ -0,0 +1,82 @@
+// 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;
+using System.Collections.Concurrent;
+using System.IO;
+using static Microsoft.CmdPal.Ext.Apps.Utils.Native;
+
+namespace Microsoft.CmdPal.Ext.Apps.Utils;
+
+/// <summary>
+/// Class to get localized name of shell items like 'My computer'. The localization is based on the 'windows display language'.
+/// </summary>
+public class ShellLocalization
+{
+    internal static readonly ShellLocalization Instance = new();
+
+    // Cache for already localized names. This makes localization of already localized string faster.
+    private ConcurrentDictionary<string, string> _localizationCache = new ConcurrentDictionary<string, string>();
+
+    /// <summary>
+    /// Returns the localized name of a shell item.
+    /// </summary>
+    /// <param name="path">Path to the shell item (e. g. shortcut 'File Explorer.lnk').</param>
+    /// <returns>The localized name as string or <see cref="string.Empty"/>.</returns>
+    public string GetLocalizedName(string path)
+    {
+        var lowerInvariantPath = path.ToLowerInvariant();
+
+        // Checking cache if path is already localized
+        if (_localizationCache.TryGetValue(lowerInvariantPath, out var value))
+        {
+            return value;
+        }
+
+        var shellItemType = ShellItemTypeConstants.ShellItemGuid;
+        var retCode = SHCreateItemFromParsingName(path, nint.Zero, ref shellItemType, out var shellItem);
+        if (retCode != 0)
+        {
+            return string.Empty;
+        }
+
+        shellItem.GetDisplayName(SIGDN.NORMALDISPLAY, out var filename);
+
+        _ = _localizationCache.TryAdd(lowerInvariantPath, filename);
+
+        return filename;
+    }
+
+    /// <summary>
+    /// This method returns the localized path to a shell item (folder or file)
+    /// </summary>
+    /// <param name="path">The path to localize</param>
+    /// <returns>The localized path or the original path if localized version is not available</returns>
+    public string GetLocalizedPath(string path)
+    {
+        path = Environment.ExpandEnvironmentVariables(path);
+        var ext = Path.GetExtension(path);
+        var pathParts = path.Split("\\");
+        var locPath = new string[pathParts.Length];
+
+        for (var i = 0; i < pathParts.Length; i++)
+        {
+            if (i == 0 && pathParts[i].EndsWith(':'))
+            {
+                // Skip the drive letter.
+                locPath[0] = pathParts[0];
+                continue;
+            }
+
+            // Localize path.
+            var iElements = i + 1;
+            var lName = GetLocalizedName(string.Join("\\", pathParts[..iElements]));
+            locPath[i] = !string.IsNullOrEmpty(lName) ? lName : pathParts[i];
+        }
+
+        var newPath = string.Join("\\", locPath);
+        newPath = !newPath.EndsWith(ext, StringComparison.InvariantCultureIgnoreCase) ? newPath + ext : newPath;
+
+        return newPath;
+    }
+}