Create ClientRegistration from OIDC Discovery

[jgrandja]

OpenID Connect clients should be capable of discovering Provider information, as defined by the OpenID Connect Discovery 1.0 specification.

This feature will greatly simplify the manual configuration of an OIDC client.

[jgrandja]

Related #4440 - complete below outstanding tasks after this issue is resolved

• Validate the iss (issuer) Claim on the ID Token
• Validate the alg value SHOULD be the default of RS256 or the algorithm sent by the Client in the id_token_signed_response_alg parameter during registration