title: Amplify Flutter: how to implement Auto Login and obtain authToken
body: <p>I'm using Amplify Flutter to implement user authentication in my Flutter app and can't figure out the following two things:</p>
  <ol>
  <li><p><strong>Auto-login</strong>: How do I implement auto-login so that users remain logged in when closing and reopening the app over time (i.e. the app remains in logged-in state indefinitely unless users specifically log out of the app)?</p>
  </li>
  <li><p><strong>authToken</strong>: When the user is logged in, how do I get the authToken needed to add to my outgoing api requests (from the app to my aws backend)?</p>
  </li>
  </ol>
  <p>Been scouring the internet (and reading through the official docs) for solutions but can't seem to find much info on this or figure it out.</p>