add translation to datacite openaire application profile

[ferrighi]

We need to create an mmd-to-openaire_datacite.xsl to support metadata output using the OpenAIRE metadata schema from https://guidelines.openaire.eu/en/latest/data/application_profile.html

This is based on datacite schema, but has some dedicated requirements.

[ferrighi]

All the elements are relatively easy to map. The only open issue is the identifier (https://guidelines.readthedocs.io/en/latest/data/field_identifier.html#d-identifier) there is a controlled list for the type:

• ARK
• DOI
• Handle
• PURL
• URN
• URL

This list does not really match our mmd:metadata_identifier, which is never a URL. We have some harvested DOI which we could handle, but the rest are not valid entries for these specifications.