Be logged out on IDP side

[llomgui]

Is your feature request related to a problem? Please describe.
With the current oidc configuration, if you go on https://domain.org/logout, it only clears the cookies from Nginx perspective, not from IDP.
As describe in Auth0 documentation, you need to redirect the user on IDP's logout endpoint.

Describe the solution you'd like
The solution is to redirect the user on IDP's logout endpoint with the correct arguments.
On the IDP side, you can specify the Nginx logout endpoint /_logout and then Nginx will redirect to a final page https://domain.org/login.

Nginx teams already done that in a previous project. Not implemented on this one.
https://github.com/nginx-openid-connect/nginx-oidc-auth0/blob/main/oidc.js#L178
https://github.com/nginx-openid-connect/nginx-oidc-auth0/blob/main/oidc_nginx_server.conf#L132

### UACs
- [x] Test and validate changes in https://github.com/nginxinc/kubernetes-ingress/pull/4986 with [updates merged to NGINX OIDC repo](https://github.com/nginxinc/nginx-openid-connect/pull/96)

[github-actions]

Hi @llomgui thanks for reporting!

Be sure to check out the docs and the Contributing Guidelines while you wait for a human to take a look at this 🙂

Cheers!

[brianehlert]

The OIDC reference implementation has been updated and NIC needs to be refreshed to align.
@danielnginx @shaun-nx

[j1m-ryan]

Hi @llomgui, this functionality will be available in 3.7.0.