Making FaceUnlock not pop up for overlays Fixes 5451837 Fixes 5446341

When the screen turns on because of an incoming phone call or
when the emergency dialer is selected, FaceUnlock is deactivated
until the phone call is completed and the screen is turned off.

This also checks for non-phone overlays.
If the lockscreen becomes unfocused while the screen is on,
we assume that the reason is an overlay and prevent FaceUnlock
from starting.  The normal clock app is not considered an overlay by
this approach, and thus it works as intended (back button
brings up FaceUnlock).

Also reverts: https://android-git.corp.google.com/g/#/c/139885/2
to make FaceUnlock appear when music is playing again

Change-Id: Id715878556667d2b7e35c30a28d91be6a4eee575