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.Shell/Helpers/SettingsManager.cs

@@ -0,0 +1,72 @@
+// 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.Collections.Generic;
+using System.IO;
+using Microsoft.CmdPal.Ext.Shell.Properties;
+using Microsoft.CommandPalette.Extensions.Toolkit;
+
+namespace Microsoft.CmdPal.Ext.Shell.Helpers;
+
+public class SettingsManager : JsonSettingsManager
+{
+    private static readonly string _namespace = "shell";
+
+    private static string Namespaced(string propertyName) => $"{_namespace}.{propertyName}";
+
+    private static readonly List<ChoiceSetSetting.Choice> _choices =
+    [
+        new ChoiceSetSetting.Choice(Resources.find_executable_file_and_run_it, "2"), // idk why but this is how PT Run did it? Maybe ordering matters there
+        new ChoiceSetSetting.Choice(Resources.run_command_in_command_prompt, "0"),
+        new ChoiceSetSetting.Choice(Resources.run_command_in_powershell, "1"),
+        new ChoiceSetSetting.Choice(Resources.run_command_in_powershell_seven, "6"),
+        new ChoiceSetSetting.Choice(Resources.run_command_in_windows_terminal_cmd, "5"),
+        new ChoiceSetSetting.Choice(Resources.run_command_in_windows_terminal_powershell, "3"),
+        new ChoiceSetSetting.Choice(Resources.run_command_in_windows_terminal_powershell_seven, "4"),
+    ];
+
+    private readonly ToggleSetting _leaveShellOpen = new(
+        Namespaced(nameof(LeaveShellOpen)),
+        Resources.leave_shell_open,
+        Resources.leave_shell_open,
+        false); // TODO -- double check default value
+
+    private readonly ChoiceSetSetting _shellCommandExecution = new(
+        Namespaced(nameof(ShellCommandExecution)),
+        Resources.shell_command_execution,
+        Resources.shell_command_execution_description,
+        _choices);
+
+    public bool LeaveShellOpen => _leaveShellOpen.Value;
+
+    public string ShellCommandExecution => _shellCommandExecution.Value ?? string.Empty;
+
+    public bool RunAsAdministrator { get; set; }
+
+    public Dictionary<string, int> Count { get; } = [];
+
+    public void AddCmdHistory(string cmdName) => Count[cmdName] = Count.TryGetValue(cmdName, out var currentCount) ? currentCount + 1 : 1;
+
+    internal static string SettingsJsonPath()
+    {
+        var directory = Utilities.BaseSettingsPath("Microsoft.CmdPal");
+        Directory.CreateDirectory(directory);
+
+        // now, the state is just next to the exe
+        return Path.Combine(directory, "settings.json");
+    }
+
+    public SettingsManager()
+    {
+        FilePath = SettingsJsonPath();
+
+        Settings.Add(_leaveShellOpen);
+        Settings.Add(_shellCommandExecution);
+
+        // Load settings from file upon initialization
+        LoadSettings();
+
+        Settings.SettingsChanged += (s, a) => this.SaveSettings();
+    }
+}