message: Send a goodbye message when quitting via diagnostics port
diff: @@ -297,7 +297,11 @@ impl Session {
  }
  };
  }
  - Action::Quit => return Ok(false),
  + Action::Quit => {
  + self.send_outcome(writer, &Outcome::success("goodbye!"))
  + .await?;
  + return Ok(false);
  + }
  };
  }
  Err(err) => {
  