Register a new user to an Auth Group independant of any organization or other access considerations. Self-registration is possible if the Auth Group has defined locked=false. Otherwise, an appropriately permissioned member of the Auth Group must create the user. Please note that the only data provided by this endpoint (or any Account API) is the id, username, and email (and creat/modify/active meta data) of the user within this AuthGroup. The Account record holds no personal information aside from this email address and an optional phone number which is only visible to that Account owner; however, if you supply profile information, a secured profile record will be generated which the account holder can administrate later.