Draft on new subject identifiers

My attempt to kill off NameID and standardize how subjects should be identified is now submitted as an initial draft and I created one of my old wiki pages for it.

https://wiki.oasis-open.org/security/SAMLSubjectIDAttr

My community has a fairly aggressive timeline to bake this into a new deployment profile at Kantara so we're hoping to fast track this relatively speaking and I would appreciate some review by anybody likely to care about it before another TC call would take place. I would probably move for CD on that call at the latest, if not over email sooner.

-- Scott