GHSA-M6VC-F87M-CC2H Doorkeeper Openid Connect: Dynamic Client Registration feature creates public clients with client_secret

Impact The DynamicClientRegistrationControllerregister action hard-codes confidential: false when creating applications dynamicclientregistrationcontroller.rb:18-25, yet the response includes a clientsecret and advertises tokenendpointauthmethodssupported: "clientsecretbasic", "clientsecretpost"...