[session] Improve handling of expired sessions [Friendica] #998
Description
Sometimes, when reopening the app after a while, your login session on a Friendica sever has expired and can not be refreshed.
This is known due to back-end limitations (no way to refresh an OAuth2 token is currently offered on Friendica), but this seems to happen a little too often and, moreover, users are not properly informed of it so they think the app is not working.