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.Bookmark/AddBookmarkForm.cs

@@ -0,0 +1,107 @@
+// 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.IO;
+using System.Text.Json;
+using System.Text.Json.Nodes;
+using Microsoft.CmdPal.Ext.Bookmarks.Properties;
+using Microsoft.CommandPalette.Extensions.Toolkit;
+using Windows.Foundation;
+
+namespace Microsoft.CmdPal.Ext.Bookmarks;
+
+internal sealed partial class AddBookmarkForm : FormContent
+{
+    internal event TypedEventHandler<object, BookmarkData>? AddedCommand;
+
+    private readonly BookmarkData? _bookmark;
+
+    public AddBookmarkForm(BookmarkData? bookmark)
+    {
+        _bookmark = bookmark;
+        var name = _bookmark?.Name ?? string.Empty;
+        var url = _bookmark?.Bookmark ?? string.Empty;
+        TemplateJson = $$"""
+{
+    "$schema": "http://adaptivecards.io/schemas/adaptive-card.json",
+    "type": "AdaptiveCard",
+    "version": "1.5",
+    "body": [
+        {
+            "type": "Input.Text",
+            "style": "text",
+            "id": "name",
+            "label": "{{Resources.bookmarks_form_name_label}}",
+            "value": {{JsonSerializer.Serialize(name)}},
+            "isRequired": true,
+            "errorMessage": "{{Resources.bookmarks_form_name_required}}"
+        },
+        {
+            "type": "Input.Text",
+            "style": "text",
+            "id": "bookmark",
+            "value": {{JsonSerializer.Serialize(url)}},
+            "label": "{{Resources.bookmarks_form_bookmark_label}}",
+            "isRequired": true,
+            "errorMessage": "{{Resources.bookmarks_form_bookmark_required}}"
+        }
+    ],
+    "actions": [
+        {
+            "type": "Action.Submit",
+            "title": "{{Resources.bookmarks_form_save}}",
+            "data": {
+                "name": "name",
+                "bookmark": "bookmark"
+            }
+        }
+    ]
+}
+""";
+    }
+
+    public override CommandResult SubmitForm(string payload)
+    {
+        var formInput = JsonNode.Parse(payload);
+        if (formInput == null)
+        {
+            return CommandResult.GoHome();
+        }
+
+        // get the name and url out of the values
+        var formName = formInput["name"] ?? string.Empty;
+        var formBookmark = formInput["bookmark"] ?? string.Empty;
+        var hasPlaceholder = formBookmark.ToString().Contains('{') && formBookmark.ToString().Contains('}');
+
+        // Determine the type of the bookmark
+        string bookmarkType;
+
+        if (formBookmark.ToString().StartsWith("http://", StringComparison.OrdinalIgnoreCase) || formBookmark.ToString().StartsWith("https://", StringComparison.OrdinalIgnoreCase))
+        {
+            bookmarkType = "web";
+        }
+        else if (File.Exists(formBookmark.ToString()))
+        {
+            bookmarkType = "file";
+        }
+        else if (Directory.Exists(formBookmark.ToString()))
+        {
+            bookmarkType = "folder";
+        }
+        else
+        {
+            // Default to web if we can't determine the type
+            bookmarkType = "web";
+        }
+
+        var updated = _bookmark ?? new BookmarkData();
+        updated.Name = formName.ToString();
+        updated.Bookmark = formBookmark.ToString();
+        updated.Type = bookmarkType;
+
+        AddedCommand?.Invoke(this, updated);
+        return CommandResult.GoHome();
+    }
+}