Theme engine: Migrate wallpaper settings to new theme engine

This was decided for a couple of reasons:

1. Lockscreen wallpaper setting was breaking when transitioning to CM's separation of wallpaper setting from Trebuchet.
2. We would lose mods for Lockscreen see through amd blur.

We will look into transitioning to CM's approach later on.
Add Entrypoint for theme sounds

Change-Id: I6da2fa782b9b88fc669144eb50c3231d031cd620