Return roles in authentication response

Problem/Motivation

It might be helpful to add a setting to return the user roles machine names on authentication to provide an alternative to core login handling.

See this core issue: 📌 User roles missing in /user/login?_format=json REST response Closed: won't fix

I think it should be a setting so it can be turned on, when needed.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes