* Check that an invite link is valid before bypassing approval mode

Fixes #10656

* Add tests

* Only consider valid invite links in registration controller

* fixup

Fix #6856
Fix #6951

and use 'if' option of context block

* Do not test PAM authentication by default

* Disable PAM tests if PAM is not enabled

* Add force_login option to OAuth authorize page

For when a user needs to sign into an app from multiple accounts
on the same server

* When logging out from modal header, redirect back after re-login

* update gem, test pam authentication

* add description for test parameters

* fix inclusion of optional group

A change introduced in #6125 prevents
`Devise::Models::Confirmable#confirm` from being called for existing
users, which in turn leads to `email` not being set to
`unconfirmed_email`, breaking email updates. This also adds a test
that would've caught this issue.

When a new user confirms their e-mail, bootstrap their home timeline
by automatically following a set of accounts. By default, all local
admin accounts (that are unlocked). Can be customized by new admin
setting (comma-separated usernames, local and unlocked only)

When case insensitivity is enabled via devise's `config.case_insensitive_keys` then `.find_for_authentication` method needs to be used instead of `.find_by` because second mentioned returns `nil` when valid email with different cases is passed.

More info https://github.com/plataformatec/devise/wiki/How-To:-Use-case-insensitive-emails

In single user mode, visitors are redirected to the single user's
profile page.  So, if you are the owner without a session, you start
from that page, click the login button and authenticate yourself
expecting you'll soon get started with the home page, but in reality
you'll get redirected back to where you started from -- your own
profile page.

This fixes the behavior by redirecting you home after login if you
have started from your own profile page.

(You may think that we need account deletions, but this way would've just orphaned the db records)

* Add a spec for signing out

* Add spec showing that suspended user gets a 403 forbidden on sign out

* Allow suspended account users to sign out

This PR fixes I18n.locale for rake middlewares. Mastodon uses Devise that depends on Warden.
Warden::Manager can be found in rake middleware. It is outside of the controller.

In the case of authentication failed, warden calls throw(:warden). At the time Warden::Manager
delegates request to failure_app to generate response and flash[:alert] after catching it.
Unfortunately, I18n.locale is already reset then because I18n.with_locale is enabled only
inside the controller. If we used I18n.locale=, Devise::FailureApp could get the current locale.

* Add recovery code support for two-factor auth

When users enable two-factor auth, the app now generates ten
single-use recovery codes. Users are encouraged to print the codes
and store them in a safe place.

The two-factor prompt during login now accepts both OTP codes and
recovery codes.

The two-factor settings UI allows users to regenerated lost
recovery codes. Users who have set up two-factor auth prior to
this feature being added can use it to generate recovery codes
for the first time.

Fixes #563 and fixes #987

* Set OTP_SECRET in test enviroment

* add missing .html to view file names

registration API