Add subscribe to VHAL proto.

The latest IVehicleHardware adds Subscribe/Unsubscribe function
to replace the existing updateSampleRate. This CL adds the
Subscribe function to protobuf definition and implements it.

Test: atest GRPCVehicleHardwareUnitTest GRPCVehicleProxyServerUnitTest
Flag: EXEMPT hal change
Bug: 328316981
Merged-In: I4f02885b77f21a215a8b282be583f76118e400ba
(cherry-picked from commit: f1a869055fcd6ea980e329e86d71ace715427d30)

Change-Id: I4f02885b77f21a215a8b282be583f76118e400ba

• automotive/vehicle/TEST_MAPPING[diff]
• automotive/vehicle/aidl/impl/grpc/Android.bp[diff]
• automotive/vehicle/aidl/impl/grpc/GRPCVehicleHardware.cpp[diff]
• automotive/vehicle/aidl/impl/grpc/GRPCVehicleHardware.h[diff]
• automotive/vehicle/aidl/impl/grpc/GRPCVehicleProxyServer.cpp[diff]
• automotive/vehicle/aidl/impl/grpc/GRPCVehicleProxyServer.h[diff]
• automotive/vehicle/aidl/impl/grpc/proto/VehicleServer.proto[diff]
• automotive/vehicle/aidl/impl/grpc/test/GRPCVehicleHardwareUnitTest.cpp[diff]
• automotive/vehicle/aidl/impl/grpc/test/GRPCVehicleProxyServerUnitTest.cpp[diff]
• automotive/vehicle/aidl/impl/grpc/utils/proto_message_converter/Android.bp[diff]
• automotive/vehicle/aidl/impl/grpc/utils/proto_message_converter/include/ProtoMessageConverter.h[diff]
• automotive/vehicle/aidl/impl/grpc/utils/proto_message_converter/src/ProtoMessageConverter.cpp[diff]
• automotive/vehicle/aidl/impl/grpc/utils/proto_message_converter/test/proto_message_converter_test.cpp[diff]
• automotive/vehicle/aidl/impl/proto/Android.bp[diff]
• automotive/vehicle/aidl/impl/proto/android/hardware/automotive/vehicle/SubscribeOptions.proto[Added - diff]
• automotive/vehicle/aidl/impl/proto/android/hardware/automotive/vehicle/SubscribeRequest.proto[Added - diff]