Clearer mapping between OIDC data type to R&E data types (eduPerson, Schac, possibly SAML Subject Identitifer)

[albertwu]

RE: 6.2.4 Scope and claims

Assuming eduPerson and Schac specs continue to be our normative spec to describe person, there should be an explicit mapping between attributes from those LDAP schemas with OIDC conventions. That probably should be done outside this doc, but needs to be referenced from here.

Ya... there is the issue with SAML Subject Identifiers.... we need a transport agnostic definition of those identifiers.