Listen to auth events
AWS Cognito Auth Plugin sends important events through Amplify Hub.
final subscription = Amplify.Hub.listen(HubChannel.Auth, (AuthHubEvent event) {  switch (event.type) {    case AuthHubEventType.signedIn:      safePrint('User is signed in.');      break;    case AuthHubEventType.signedOut:      safePrint('User is signed out.');      break;    case AuthHubEventType.sessionExpired:      safePrint('The session has expired.');      break;    case AuthHubEventType.userDeleted:      safePrint('The user has been deleted.');      break;  }});