Refactor serial worker
Serial worker implement a functionality to go across ordered messages of stream. This MR switched from get_next to get_by_id asapo API. The choice of start_id is now transparently on client side.
Serial worker implement a functionality to go across ordered messages of stream. This MR switched from get_next to get_by_id asapo API. The choice of start_id is now transparently on client side.