Add lock icon to bouncer when scrimmed

Lock icon needs to be reparented to the bouncer when we're
asking for a pin on top of the notification panel, since the
scrim would cove the whole lock screen.

Fixes: 129160870
Test: atest KeyguardBouncerTest
Test: atest StatusBarKeyguardViewManagerTest
Test: double tap notification
Test: swipe up to unlock
Test: swipe to shade locked, tap notification
Test: repeat with and without pin
Change-Id: I476ab2822da0040cfcfe7f8bc775b76407f0c613