Receive review from tech-lead on oauth helpers

[agoose77]

Definition of done

• Tech lead reviews https://2i2c.org/jupyterhub-oauthenticator-authz-helpers/ repo
• Tech lead provides feedback that can be refined into follow up actions

[yuvipanda]

Can you add examples of how this would be used with auth_state_groups_key https://github.com/jupyterhub/oauthenticator/blob/97f4ad2e0a4a42bc808fd7a5c68df53850066639/oauthenticator/oauth2.py#L389?