Add additional `CITATION.cff` fields

[hlmore]

Somesy is based on the CITATION.cff schema, but doesn't support all the same fields. Now that Zenodo can use metadata from CITATION.cff, it would be nice if Somesy could support more fields so that it could be part of a full Zenodo pipeline.

I would suggest that the most urgent fields from CITATION.cff for Somesy to add are:

• doi
• identifiers
• type

Links:

• CITATION.cff fields: https://github.com/citation-file-format/citation-file-format/blob/main/schema-guide.md#index
• Somesy fields and equivalents: https://materials-data-science-and-informatics.github.io/somesy/main/manual/#metadata-mapping