This commit adds a configuration guide for the newly introduced
OpenID Connect realm. The guide is similar to the style of the
SAML Guide and shares certain parts where applicable (role mapping)
It also contains a short section on how the realm can be used for
authenticating users without Kibana.
Co-Authored-By: Lisa Cawley <lcawley@elastic.co>
Backport of #41423 and #42555
* This commit is part of our plan to deprecate and ultimately remove the use of _xpack in the REST APIs.
- REST API docs
- HLRC docs and doc tests
- Handle REST actions with deprecation warnings
- Changed endpoints in rest-api-spec and relevant file names
- Add the authentication realm and lookup realm name and type in the response for the _authenticate API
- The authentication realm is set as the lookup realm too (instead of setting the lookup realm to null or empty ) when no lookup realm is used.
