- Tab between register and sign in forms
- Add individual input validation error messages
- Validate username
- Update many styles for all login-box forms
The helper constructs the path for a given oauth provider since Devise 4.0 deprecated passing the provider to the omniauth authentication path.
Fixes#18110.
Avoids an empty Sign in box when signup_enabled? is false, and avoids
showing "No authentication methods configured" unless there really are none.
OmniAuth signin gets its own file for consistency with signin and signup and LDAP.