AmbientIndication: Move into container

This allows fixing the following bugs:
- ambient indication should be hidden outside keyguard
- ambient indication should animate with the unlock hint
- ambient indication should fade out when unlocking

Fixes: 38289189
Test: observe that the things above are working correctly
Change-Id: I34aff69bb5621a3f12c25e87eac6a89c8c7e2165