Keyguard: Refactoring for improving trusted unlock while occluded

- Adds a trusted signal from Keyguard to PhoneWindowManager
- Allows PhoneWindowManager to exempt DISMISS_KEYGUARD windows from force hiding
- Allows PhoneWindowManager to dismiss Keyguard while occluded

Bug: 27410215
Change-Id: I3ad490b64a5805b6f3888a9f37fcfbdd0116395e
10 files changed