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
diff --git a/automotive/vehicle/aidl/impl/grpc/GRPCVehicleProxyServer.cpp b/automotive/vehicle/aidl/impl/grpc/GRPCVehicleProxyServer.cpp
index af3dd59..558ab2f 100644
--- a/automotive/vehicle/aidl/impl/grpc/GRPCVehicleProxyServer.cpp
+++ b/automotive/vehicle/aidl/impl/grpc/GRPCVehicleProxyServer.cpp
@@ -164,6 +164,17 @@
     return ::grpc::Status::OK;
 }
 
+::grpc::Status GrpcVehicleProxyServer::Subscribe(::grpc::ServerContext* context,
+                                                 const proto::SubscribeRequest* request,
+                                                 proto::VehicleHalCallStatus* status) {
+    const auto& protoSubscribeOptions = request->options();
+    aidlvhal::SubscribeOptions aidlSubscribeOptions = {};
+    proto_msg_converter::protoToAidl(protoSubscribeOptions, &aidlSubscribeOptions);
+    const auto status_code = mHardware->subscribe(aidlSubscribeOptions);
+    status->set_status_code(static_cast<proto::StatusCode>(status_code));
+    return ::grpc::Status::OK;
+}
+
 ::grpc::Status GrpcVehicleProxyServer::CheckHealth(::grpc::ServerContext* context,
                                                    const ::google::protobuf::Empty*,
                                                    proto::VehicleHalCallStatus* status) {