QoL Improvement - Detect when authorisation with a Pod has expired and streamline re-authentication

Initially discussed in the Android matrix chat, I believe there is room for improvement on how the process works when authentication between FW for Android expires.

The current user experience for this is as follows

1. User may not use the app for 14 days, token expires
2. The next time the user uses the app, they note that content won't play/refreshing removes all content
3. User then has to go into settings to Sign Out
4. They then have to re-enter their pod address
5. Complete the app authentication

I believe this can be simplified to something of the following effect:

1. App token expires
2. App checks on next load whether content is available
3. If content is not available due to token expiry, boot user back to sign in screen
4. Retain last used session URL to save time

Even better, would be a prompt that is just a one button press to restart the auth session without even being booted back to the instance URL screen. I feel the only time users should see that is if they have signed out on purpose either to change pods or other reasons.