Merge tag 'android-8.1.0_r81' into staging/lineage-15.1_merge-android-8.1.0_r81

Android 8.1.0 Release 81 (6780335)

* tag 'android-8.1.0_r81':
  Mark implicit PendingIntents as immutable
  RESTRICT AUTOMERGE Do not set referrerUri on SessionInfo for non-owners
  Add missing isShellUser check
  Remove unused intent in NiNotification