reroute datacite // crossref validation to DataCite graphQL

Adapt the file toolbox/extractor/publication_validator.py such that instead of querying metadata both from the Datacite and Crossref APIs, the module now queries metadata only from the DataCite GraphQL API.

Documentation:

• https://api.datacite.org/graphql
• https://support.datacite.org/docs/datacite-graphql-api-guide

we have the chance to request dataset or publication here and see if we get something out of here for validation. registrationAgency can tell us where the publication was registered (datacite, crossref, etc…) and many more information is available here.