ProxyHTTP now processes middleware Handler before executing the request.
A chain of handlers is now executed and appropriate response status
codes are sent.
We take advantage of the JWTValidator middleware and attach it to an
ingress rule based on Access configurations. We attach the Validator
directly to the ingress rules because we want to take advantage of
caching and token revert/handling that comes with go-oidc.
This adds a new verifier interface that can be attached to ingress.Rule.
This would act as a middleware layer that gets executed at the start of
proxy.ProxyHTTP.
A jwt validator implementation for this verifier is also provided. The
validator downloads the public key from the access teams endpoint and
uses it to verify the JWT sent to cloudflared with the audtag (clientID)
information provided in the config.