Support dc+sd-jwt for SD-JWT VCs

[TimoGlastra]

The identifier has changed: https://openid.github.io/OpenID4VP/openid-4-verifiable-presentations-wg-draft.html#name-ietf-sd-jwt-vc-2

It is recommend to accept both a reasonable transitional period.

Note that this draft used vc+sd-jwt as the value of the typ header from its inception in July 2023 until November 2024 when it was changed to dc+sd-jwt to avoid conflict with the vc media type name registered by the W3C's Verifiable Credentials Data Model draft. In order to facilitate a minimally disruptive transition, it is RECOMMENDED that Verifiers and Holders accept both vc+sd-jwt and dc+sd-jwt as the value of the typ header for a reasonable transitional period.