Authservice Support For Non Keycloak OIDC Endpoints

Allow for authservice chains to utilize non-keycloak endpoints for authorization and token URIs, and do not iterate over those values in a given chain if they are already specified.

Currently when a full authservice chain with all options declared is present in the authservice values, the authorization_uri and token_uri get overwritten even when .Values.sso.oidc options are not set.

Setting:

addons:
  authservice:
    values:
      chains:
        kiali:
          authorization_uri: https://CUSTOM_URL/ENDPOINT/SERVICE

It gets replaced with:

authorization_uri: "https://login.dso.mil/auth/realms/baby-yoda/protocol/openid-connect/auth"

Inside the authservice configuration secret.