Level assigned at registration needs to be aware of new MappingLevel API

[categulario]

When a new user is registered it is assigned a level based solely on her contributions. This needs to be modified considering that MappingLevel is now a table instead of an enumeration.

Considerations

• Some levels will require approval.
• Badges can be assigned without approval.

Locations

• backend/services/users/user_service.py (register_user_with_email())
  • /actions/register/
• backend/services/users/user_service.py (register_user()) assigns level
  • backend/services/users/authentication_service.py (AuthenticationService.login_user())
    • backend/api/system/authentication.py (/authentication/callback/)

Discussion

Applies the same as for issue #6878