OIDC: Use 'userinfo' endpoint when userinfo data are not sent along with ID token.

[psrok1]

Feature Category

• Correctness
• User Interface / User Experience
• Performance
• Other (please explain)

Describe the problem

In current implementation we don't use /userinfo endpoint at all because Keycloak sends user information along with ID token. Unfortunately it's not that common as we thought.

Describe the solution you'd like

If there are no extra information about the user: e-mail, username (["preferred_username", "nickname", "name"]) in the /token response, ask /userinfo.