message: Implement handling AgentCommand::SendAck.
diff: @@ -114,6 +114,10 @@ impl AgentCommandExecutor {
  info!(target: "agent_command_executor", "Send command received");
  self.send(connection_id, msg, cb)
  }
  + AgentCommand::SendAck(cmd_id, res) => {
  + info!(target: "agent_command_executor", "SendAck command received");
  + self.send_callbacks.borrow_mut().remove(&cmd_id).unwrap()(res.map_err(From::from));
  + }
  _ => unimplemented!(),
  }
  }
  