Using Issuer to receive OAuth Token Endpoint

[Lyphion]

Is your feature request related to a problem? Please describe.

To create a new RabbitMQ Connection with the OAuth2ClientBuilder it is very annoying, that I have to manually provide the TokenEndpoint of my Issuer to the Builder, instead of the Issuer itself.
An option to choose whether you provide the Issuer or the TokenEndpoint directly would help.
This feature requires that the Issuer supports OpenID Connect and the discovery page. The RabbitMQ OAuth 2.0 Authentication Backend supports OpenID Connect and the discovery endpoint.

Describe the solution you'd like

In general the TokenEndpoint used for the connection can be extracted automatically from the discovery page (when using OpenID Connect) of the Issuer (/.well-known/openid-configuration -> 'token_endpoint'-Field).
It would really help if the OAuth2ClientBuilder can accept an Issuer instead of the TokenEndpoint and load/parse the Endpoint by itself while building the client, or an separate Builder for OpenID Connect would be implemented/used.

Describe alternatives you've considered

No response

Additional context

No response

[michaelklishin]

@Lyphion would you mind providing some code examples? I find the current description too vague to be actionable => converting to a discussion.