Enable json-ld testing

[PatStLouis]

We need to ensure that documents are valid w3c VC.

When we received feedback on our implementation, an alternative was proposed, however this proposal broke VCDM 2.0 conformance at the cost of meeting the current schema validation of the DCC, resulting in a credential that would be rejected by other conformant VC implementations. It would be important to ensure VC do not silently drop attributes by including a json-ld processing test. A simple compaction with dropped attribute detection would be a good start.