Feature: disable password login

WP [#7662](https://www.openproject.org/work_packages/7662)

Requires merging of [this](https://github.com/finnlabs/openproject-self_registration_by_mail/pull/17) into `openproject-self_registration_by_mail`.
I don't really like this in a concern as we only used this concern to split up the way too large AccountController. 

I don't really have a better idea. What about using `AccountController.disable_password_login?`?

@linki Do you have an opinion on this?