Allow authenticated user role

There may be circumstances where the basic authenticated_user role is the only role that a user will need or should choose. If the role field is required and the authenticated_user role is not exposed because it is currently explicitly hidden by select_registration_roles_all_roles, this would be problematic if you do not want a user to select a more complex role. I would propose a configuration setting that hides the authenticated_user by default, but allows this setting to be changed.

In my own use case, most users will take a basic role. I am keeping authenticated_user but have renamed it to a suitable role name. I do want users to be able to select this most basic role - in addition to two more roles with privileged access. Not exposing authenticated_user would simply mean I would be required to create a fourth superfluous role. This would be a pain for maintenance of permissions and is unnecessary. In my case, I have also applied the patch to use the label of the authenticated_user role, which is not Authenticated User.

The solution is to make a simple checkbox field for 'Display the authenticated user role' which can be checked to allow the authenticated_user role to be listed as an option.