Unfocus wallpaper updated with permission

This commit is a refractoring of ag/20338859. The change gives apps
with android.permission.ALWAYS_UPDATE_WALLPAPER to update the wallpaper
even if the wallpaper is out of focus.

The permission is given to home role owners, and is intended to be used
by wear targets only.

Bug: 271132915
Test: run cts -m CtsWallpaperTestCases
Change-Id: I4471a7e13ce8f3c52e1f5e6288a5e0f2b290955b