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`.
[Yes](https://github.com/opf/openproject/blob/feature/disable_password_login/lib/redmine/menu_manager/top_menu_helper.rb#L125).