refactor: Reduce API calls required to watch status during ActorClient.call

[Pijukatel]

Description

• Add ResponseWatcher protocol.
• Add response_watcher arguments to wait_for_finish methods.
• wait_for_finish uses an optional response_watcher callable each time it processes the API response.

Previously, StatusWatcher was periodically calling RunClient.get to get the status and status message of another Actor run. Since ActorClient.call is already periodically calling RunClient.get through RunClient.wait_for_finish, there is no need for StatusWatcher to do the API calls again; it just needs to re-use the responses of already available in RunClient.wait_for_finish. It can do so, by passing the response_watcher argument to wait_for_finish.