[FEATURE] Support rate limiting on roles and backend roles

[derek-ho]

Is your feature request related to a problem?
The supported types of rate limiting today are by username and by ip address. I think that functionality can greatly improve if we support two additional types: roles and backend roles. Backend roles could be useful to support rate limiting in SSO/IDP use cases. Roles could be more useful to implement rate limiting on a higher level, with user groups, similar to the way that permissioning works today.

What solution would you like?
Support rate limiting on roles and backend roles type
What alternatives have you considered?
None
Do you have any additional context?
No

[stephen-crawford]

[Triage] Hi @derek-ho thank you for filing this issue. I will leave this issue open but we can connect discussion of this issue to the similar one you opened #4652 and go from there.