Update OIDC implementation to work with tls-passthrough

[vepatel]

As described in #7278,

In TLS-passthrough mode NIC at layer 4, it doesn't terminate SSL/TLS, so it never sees or can add http headers. It simply forwards the encrypted TCP stream to oidc, typically with proxy protocol enabled:

listen unix:/var/lib/nginx/passthrough-https.sock proxy_protocol;

We need to modify https://github.com/nginx/kubernetes-ingress/blob/main/internal/configs/oidc/oidc_common.conf based on https://github.com/nginxinc/nginx-openid-connect?tab=readme-ov-file#configuring-nginx-plus

something like:

map $proxy_protocol_server_port $effective_port {
  "" $server_port;
  default $proxy_protocol_server_port;
}
map $http_x_forwarded_port $redirect_base {
  "" $proto://$host:$effective_port;
  default $proto://$host:$http_x_forwarded_port;
}

[github-actions]

Hi @vepatel 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!