Implement new rotation policy.

Rotation lock does not override NOSENSOR mode anymore.

Centralize the rotation policy settings into a new class shared by
the System UI and Settings applications.

Add a new setting to specify whether rotation-lock is being hidden
because the "auto-rotate screen" option has been toggled in the
Accessibility settings panel.

Bug: 6523269
Change-Id: I15173280d25bc5d101e89a9c65913aefc53fc33a