Move display power controller to display manager service. (DO NOT MERGE)

This refactoring is in preparation for enabling the display manager
to have more control over the blanking state of individual displays.
There are no functional changes.  Some bits will be cleaned up in
a subsequent patch.

Bug: 13133142
Change-Id: Ib811835e8757449c7899ac61807029baaf998161
10 files changed