title: Flutter - remove auto login after registration in Firebase
body: <p>I've got a problem with registration in Flutter. As far as I see, firebase sign in user automatically after registration. I want to prevent this action, because in my app every user must be confirmed. </p>
  
  <p>I saw the solution for this case in other topic but IMO, calling signout after registration isn't good idea because we need to do additional step. Is there any possibility to remove sign in after registration in prettier way?</p>
  
  <p>Thanks!</p>