IANA registrations needed for openid4vci-proof+jwt and openid4vci-proof+cwt

[Michael Jones]

We need to register the media types application/openid4vci-proof+jwt and application/openid4vci-proof+cwt with IANA.

We may need to also register the media type suffix +cwt if that hasn’t already been done by others by the time we need it.

[Mark Haine]

Migrated to GitHub

https://github.com/openid/OpenID4VCI