NGINX Plus: OpenID Connect

[mpstefan]

As an application developer using NGF
I want to define an OpenID Connect endpoint to configure my JWT validation for my HTTPRoute
So that my JWT keys can be stored and managed securely on a remote endpoint.

Background

This is a continuation of authentication work started with #835. Most large organizations are going to utilize an identity provider to handle JWT authentication, and so this epic should come as a swift follow up to local JWT authentication. By defining an OIDC endpoint, we can integrate with these identity providers and relieve the authentication burden of JWT authentication from the application developers.

Not included in this epic:

• Validation of specific JWT fields

Acceptance

• When the user specifies a need for