fix: add missing presentationSubmission field + tests

[wolf4ood]

WHAT

add missing presentationSubmission field + tests

Closes #159

[arnoweiss]

Is there a functional necessity to add this? The issue sounds like the motivation is only that it's "required" by the DIF Presentation Exchange spec.

[wolf4ood]

Yes it's actually required when using presentationDefinition in the PresentationQueryMessage. I forgot to change the text spec in this case

[arnoweiss]

Thanks for adding to the spec text. I think this opens a larger question on the relationship between the DIF Presentation Exchange spec and the DCP - should something be required in DCP if it is required in DIF PE?

[arnoweiss]

As per discussion among the committers Jan 16th, DCP reuses parts of the DIF Presentation Exchange selectively.

This PR expands that selection by adding metadata that helps the client parse the presentations. This is a convenience feature only provided by the option to query the CredentialService with a presentationDefinition yielding a presentationSubmission. Clients are freed of the requirement to introspect the presentation to obtain information like vc-data-model version, jwt/json-ld etc.