Update datacite metdata to add old accession codes as altId

[rushirajnenuji]

for alternative identifier, I don't think you need to add the doi as that is already listed in the identifier field of the metadata. Other accession numbers, partcicularly the original vegbank accession codes from the identifiers table would be a nice to have, as it would formally associate the old access strings and the new DOIs and vb codes. Those might have the form vegbank:VB.xxxxxxxxxxx and could also link to identifiers.org for the resolver

feedback from @mbjones on Slack

• related:
  • issues: create functions to generate DataCite metadata #311