* Fix 2FA challenge not appearing for non-database users

Fix #11685

* Fix account deletion not working when using external login

Fix #11691

Allow access to account settings, 2FA, authorized applications, and
account deletions to unconfirmed and pending users, as well as
users who had their accounts disabled. Suspended users cannot update
their e-mail or password or delete their account.

Display account status on account settings page, for example, when
an account is frozen, limited, unconfirmed or pending review.

After sign up, login users straight away and show a simple page that
tells them the status of their account with links to account settings
and logout, to reduce onboarding friction and allow users to correct
wrongly typed e-mail addresses.

Move the final sign-up step of SSO integrations to be the same
as above to reduce code duplication.

Define `Settings::BaseController#set_body_classes` so that sub classes
inherit `Settings::BaseController` don't need to define
`#set_body_classes` agein.

account before removing content for quicker feedback to end-users

* Add form for account deletion

* If avatar or header are gone from source, remove them

* Add option to have SuspendAccountService remove user record, add tests

* Exclude suspended accounts from search