GNSS HAL & VTS for Duty Cycling & Low Power APIs.

Defintions for 2 GNSS Android P features:
- The Duty Cycling OFF API to enable high accuracy applications development
- The Low Power Mode GNSS API to save power when indoor

VTS tests for both features.

Bug: 64009176
Test: hidl-gen/compile/build checks, no functional tests yet
Change-Id: I4a41757e4ad6747f22a7e9ae1e0024f083c5fbfb