Implement getSupportedValuesLists in DefaultVehicleHal.

Implement getSupportedValuesLists in DefaultVehicleHal. This CL
also updates the doc to allow per [propId, areaId] to still kept
HasSupportedValueInfo as null for new VHAL implementation. This allows
VHAL implementation to opt-in the new supported values API on a
per [propId, areaId] basis.

Flag: EXEMPT HAL impl
Test: atest DefaultVehicleHalTest
Bug: 382563296
Change-Id: I931fe18c2e326c46446033204e8fdf63d5c10c8a