ForwardAuth as authentication method

[kaznovac]

Is your feature request related to a problem? Please describe.
I would like to configure authentication against rest-like JWT 3rd party auth provider Cloudflare Access/ZeroTrust in similar manner as Traefik ForwardAuth can do.

Describe the solution you'd like
See the Traefik ForwardAuth documentation.

Describe alternatives you've considered

• Creating separate Github OAuth Application (complicated - as than i have to split the authenticators in the Cloudflare Access)
• Spin local dedicated OAuth service in my cluster like Authelia, Keycloak, ... (redundant - yet another service to manage and keep up to date)

Additional context

[muonzoo]

This would be quite nice to have as it simplifies things considerably.