Description

This is follow-up to #37110 .

Once we have switch for standard token exchange on client, we can integrate it also with the https://openid.net/specs/openid-connect-registration-1_0.html#ClientMetadata . If the token-exchange grant is available in the grant_types supported when client is being registered/updated, we can enable standard token exchange on the client like we're doing for other grants.

Similarly we can return token-exchange grant type in the OIDC client GET request if enabled on the client.

NOTE: Related class is DescriptionConverter .