Add HW_KEY_INPUT to DefaultVehicleHal

Having this property available allows one to simulate key events via Vhal Emulator for testing/debugging purposes

Test: manual
Exempt-From-Owner-Approval: CL against code owned by Automotive team
Change-Id: I1de84c616c6611b8562f9c4442195829869f224d
(cherry picked from commit cbc10191c3d56490a646a472635e8babc397cb44)