[Feature Request] Public API to parse and return CNF

[keegan-caruso]

Is your feature request related to a problem? Please describe.

I need a public API that can parse and return a CNF claim into a domain object.

Cnf logic does currently exist, but it is internal and it is in the SignedHttpRequest project.

The public APIs should move to a lower project, likely M.IM.Tokens. This shouldn't be a problem for cross version setups as SignedHttpRequest has low usage and is a leaf dependency with the I.M solution