GRPC connector state endpoint

Currently we have an endpoint for updating a connector config. We need to either allow updating the state through that endpoint or add a separate one specifically for updating the state (e.g. setting the position). The assignee should figure out which approach to take and implement it.

Start by inspecting the existing gRPC connector-config update endpoint and how connector state, including position, is represented. Decide whether state belongs in that endpoint or needs a separate endpoint, then verify that the chosen API can update state and position as requested.

Written by the indexing model from the issue text.