Restrict cross-user wallpaper inspection Don't provide information about published wallpaper resources across user boundaries unless the caller holds full cross-user permission. Bug: 193800652 Test: atest WallpaperManagerTest Test: manual POC Change-Id: Ia2944dd32fdae47657a6683125eb3da54e6a2d2e (cherry picked from commit be08e04092109e79423bf9e9412b2fe4203c0d02)