[PT Run] Option for override theme (#7355)

* option for override PT Run theme

* fix startup theme detection and moved strings in resources

* xaml fixed

* fix title spacing

* launcher theme fix

moved theme enum
removed settings direct access

* missing files

* theme manager dispose removed

Co-authored-by: Clint Rutkas <clint@rutkas.com>

src/common/ManagedCommon/Theme.cs

@@ -0,0 +1,17 @@
+// 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.
+
+namespace ManagedCommon
+{
+    public enum Theme
+    {
+        System,
+        Light,
+        Dark,
+        HighContrastOne,
+        HighContrastTwo,
+        HighContrastBlack,
+        HighContrastWhite,
+    }
+}