Escalate HeadsUp when dreaming starts

1. When dreaming starts before locking, notifications can remain
pinned. This is because the device is locked without
screen off, and HeadsUp are not escalated.
As a result is the pinned heads up shown behind the bouncer
when unlocking.
In this case touchable bound is limited to headsup bounds,
so the user can't unlock at all.

2. Escalate HeadsUp when bar state changes to KEYGUARD

3. This also fixed a bug where the bouncer isn't touchable
When device is occluded and locked, HeadsUp can appear.
If the user then clicks on the HeadsUp and try to send
pending intent, Bouncer can be shown without expanding
panel.

Bug:30820511
Change-Id: I8604c9d00d839d773b32d8b913dfdcd2ed72f1dd