CDM profile API

This introduces API for devs to request a "watch" profile,
as well as an optional "persistent CDM grants", e.g. for devices
with wifi/LTE.

This also introduces a permission that will be mandatory for apps
to declare in the manifest when opting into the above

CTS-Coverage-Bug: 172290699
Bug: 165951651
Test: presubmit
Change-Id: Ie5016c92855f33edb46fa8eb7ae2a9226e29cdda