basic power management service

- handle boot complete and shutdown
- skeleton code for deep sleep added. Complete
  implementation requires kernel interaction which is TBD.
- handle display on / off with keeping display on with wakelock
- added interface for implementing garage mode
- tested with hal mocking only

bug: 25348217

Change-Id: Iae64ee7a16c861edd5473e392589e7e7213bd52b
(cherry picked from commit 099bc004632a2d274a11a5c436d718cba362ddc6)
12 files changed