Automatically assemble a valid RO-Crate JSON file from metadata in the container

[apirogov]

We can use pyld and use that to transform our redundant and nested JSON-LD into normalized form.

from pyld import jsonld
jsonld.compact(jsonld.flatten(imgmeta.dict()),"https://w3id.org/ro/crate/1.1/context")

Some things to consider:

• pyld chokes on the normal schema.org context, but works when given the direct link to the json file see here for URLs
• In any case, the transformations should work offline so we should maintain copies of the needed contexts in the packages
• For pyld transformations then we would need to search/replace canonical context URLs with our local context loaded from file (just assign the same dict, it is efficient due to sharing)