Immersive dark mode + Theme Listener (#18315)

* C++ impl of immersive dark mode

* Stop using the hardcoded value.

* Conjured up theme listener based on registry.

* Update MainWindow.xaml.cpp

* Update expect.txt

* Moved themehelpers to the common themes lib.

* Ported theme helpers back to .NET

* Update expect.txt

* Updated C# Theme Listening logic to mimic the one from Windows Community Toolkit.

* Replaced unmanaged code for RegisterForImmersiveDarkMode with unmanaged ThemeListener class.

* Fix upstream changes

* Update ThemeListener.h

* Update ThemeListener.h

* Proper formatting

* Added handler to Keyboard Manager.

* Update EditKeyboardWindow.cpp

* Added dwmapi.lib to runner, removed condition from additional dependencies.

* Update PowerRenameUI.vcxproj

* Added new deps for ManagedCommon to Product.wxs

* Crude attempts and understanding installer

* Removed Microsoft.Win32.Registry.dll from product.wxs.

* Updated dictionary

* Renamed ThemeListener class file for consistency, removed unused CheckImmersiveDarkMode in theme_helpers.

* Update Themes.vcxproj

* Update theme_listener.cpp

* Removed SupportsImmersiveDarkMode version check

* Removed SupportsImmersiveDarkMode version check

* Whoops

* Update expect.txt

src/common/ManagedCommon/ThemeHelpers.cs

@@ -0,0 +1,37 @@
+// 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.Linq;
+using System.Runtime.InteropServices;
+using Microsoft.Win32;
+
+namespace ManagedCommon
+{
+    // Based on https://stackoverflow.com/a/62811758/5001796
+    public static class ThemeHelpers
+    {
+        [DllImport("dwmapi.dll")]
+        private static extern int DwmSetWindowAttribute(IntPtr hwnd, int attr, ref int attrValue, int attrSize);
+
+        internal const string HKeyRoot = "HKEY_CURRENT_USER";
+        internal const string HkeyWindowsTheme = @"SOFTWARE\Microsoft\Windows\CurrentVersion\Themes";
+        internal const string HkeyWindowsPersonalizeTheme = $@"{HkeyWindowsTheme}\Personalize";
+        internal const string HValueAppTheme = "AppsUseLightTheme";
+        internal const int DWMWAImmersiveDarkMode = 20;
+
+        // based on https://stackoverflow.com/questions/51334674/how-to-detect-windows-10-light-dark-mode-in-win32-application
+        public static AppTheme GetAppTheme()
+        {
+            int value = (int)Registry.GetValue($"{HKeyRoot}\\{HkeyWindowsPersonalizeTheme}", HValueAppTheme, 1);
+            return (AppTheme)value;
+        }
+
+        public static void SetImmersiveDarkMode(IntPtr window, bool enabled)
+        {
+            int useImmersiveDarkMode = enabled ? 1 : 0;
+            _ = DwmSetWindowAttribute(window, DWMWAImmersiveDarkMode, ref useImmersiveDarkMode, sizeof(int));
+        }
+    }
+}