[OCTRL-991]: Include timestamp in state related gRPC calls

[justonedev1]

I added timestamp to all gRPC calls replies which is int64 unix timestamp in milliseconds.

[knopers8]

Thank you! My only concern is related to the point in time that these timestamps are taken. Sometimes it is at the moment of receiving the request, sometimes just before replying. If the request processing takes very little time, I guess it does not matter, but otherwise it could potentially be confusing. How about taking the timestamp always at the beginning of the call? This way it should bring minimal boilerplate code, but keep the behaviour consistent.

[justonedev1]

I changed the code to address what you said. Please don't merge this after approving, I need to squash the fixup commit after.