OpenID Connect Core 1.0 and Discovery 1.0 support

Limited to OpenID provider conformance profiles "Basic" and "Config":

- Support for features mandatory to implement for all OpenID Providers,
  not the feature set for Dynamic OpenID Providers
- Only Authorization Code Flow, no support for Implicit/Hybrid Flow
- Only code response type, no support for token/id_token
- Server metadata is served at /.well-known/openid-configuration

Additional/optional features:

- Support for "claims" parameter
- Support for standard scopes "profile" and "email"
- Support for non-standard scope/claim "groups" (in violation of RFC 9068)

Compatability with existing (working) uffd client setups: Authorization
requests without the "openid" scope behave the same as before  Prior to this
change authorization requests with the "openid" scope were rejected by uffd.

This change adds direct dependencies to pyjwt and cryptography. Prior to this
change both were already transitive dependencies of oauthlib.