RFC 8414 .well-known/oauth-authorization-server metadata

[n2ygk]

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

RFC 8414 Oauth Server metadata endpoint not implemented.

Describe the solution you'd like

Implement RFC 8414 OAuth server metadata endpoint (which is similar to the OIDC .well-known/openid-configuration/.

Describe alternatives you've considered

Additional context

[n2ygk]

This functionality is already available upstream in https://github.com/oauthlib/oauthlib/blob/v3.2.0/docs/oauth2/endpoints/metadata.rst. Just need to use it.