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)
1 file changed