Add an OIDC sample that uses Redis implementations

Expected Behavior

It is possible to enhance the documentation here to show how one can implement this with Redis? The OIDC Session Registry (for BackChannel Logouts)

https://docs.spring.io/spring-security/reference/reactive/oauth2/login/logout.html#_customizing_the_oidc_provider_session_strategy

Current Behavior

Currently because of a memory leak issue:
https://github.com/spring-projects/spring-security/issues/14558

I don't implement OidC. See my implementation here:
https://github.com/dreamstar-enterprises/docs/blob/master/Spring%20BFF/BFF/src/main/kotlin/com/frontiers/bff/auth/repositories/oidcsessionregistry/OidcSessionRegistryConfig.kt

But it would be nice to know how to use it.

This is in my main config file here (but it is turned off):
https://github.com/dreamstar-enterprises/docs/blob/master/Spring%20BFF/BFF/src/main/kotlin/com/frontiers/bff/auth/BffSecurityConfig.kt#L189

Context

How has this issue affected you?

I am in month 3 of my Spring BFF login page. It would be nice to know how to properly implement my BFF with backchannel logout

Start with the referenced Spring Security documentation section on customizing the OIDC provider session strategy, then review the linked OidcSessionRegistryConfig.kt and BffSecurityConfig.kt examples. Add a sample showing how to use Redis for the OIDC Session Registry and back-channel logout, with the documentation making the setup and usage clear.