Require credential authentication when deleting a user

Since deleting a user is an irreversible and high-impact action, Lock Screen in added after confirmation dialog when a user tries to remove themselves or an admin removes another user.

Bug: 342395399
Test: atest UserSettingsTest && atest UserDetailsSettingsTest
Flag: android.multiuser.require_pin_before_user_deletion
Change-Id: Ibcebe3f5391a423d451a387fe708d07d96604d4f