Auth: Handle invalid account

[DaVinci9196]

#2731 (comment)
Based on @fynngodau’s solution, use notifications to inform users whether their account has expired. Users can choose to log in again or log out.
Choosing to re-login will be handled based on the newly added reauth interface.

[lucasmz-dev]

Nice! Great to see this fixed 😭😭😭

[fynngodau]

Many thanks for implementing this feature. However, as a regression, the UserSatisfyRequirements resolution feature no longer works with these changes.

[fynngodau]

One thing I noticed is that reauth is not possible if Android ID has changed (i.e. when microG data has been deleted, but accounts were kept). This should be relatively easy to fix, but I don't think it needs to be solved in this PR. 🙂

[fynngodau]

When testing this PR, I removed some specific devices from the Security tab in myaccount. A few days later, unrelated to this PR, I was not able to sign in (or reauth) from microG until I changed Android ID; perhaps the device was locked out in a way microG is unable to recover from? The server response was only a generic error.

[fynngodau]

Thanks for the improvements. Reauth and enterprise setup both work at the same time now. 👍

I'm not entirely happy with the UI choices made for the notification, but that's for @mar-v-in to decide.