Merge changes from topic "caitlinshk-csi-setlockscreenuser" into udc-qpr-dev

* changes:
  [CS] 6/N=6: Remove CSI's wallpaper tracking & CS#setLockscreenUser.
  [CS] 5/N: Move WallpaperController to WallpaperRepo.
  [CS] 4/N: Remove wallpaperSupportsAmbientMode from shade window.