Download DOI - add metadata for parent DOIs

[nickdos]

ALA data download DOIs have an associated list of data resources and datasets, etc. Many of the datasets, data resources, collections, etc., already have an associated DOI (minted by GBIF).

• [ ] send the list of parent DOIs in the metadata when minting the download DOI
• [ ] back-fill old/historical DOIs with dataset DOI links (both in metadata for DOI and in stored data in DOI-service)

Most of the code required for this issue will need to go in biocache-service but putting the issue in this repo for now. Please generate a specific issue in biocache-service when actioning this issue.

[adam-collins]

Is there still benefit in doing this?