Transform layer between Metacat and OSTI library

[taojing2002]

OSTI will release ELINK 2.0 XML/JSON in Jan. 2025. This ticket describes the changes OSTI made and what we should do.

On Thursday, the NCEAS' team talked about how to avoid a new Metacat release while we still support those new features in the new OSTI library. We are thinking to create a new layer between Metacat and OSTI library. This new layer can transform the xml doc, which is generated by Metacat, to a new format, either ELINK 2.0 XML or JSON by configuration. Then the OSTI library can send the transformed messages to the server. So Metacat doesn't need change anything since it still can send the messages in the old way. Where is the new layer located? Maybe the first round we can put it in the OSTI library. So it can be self-contained.

In the future, we can make this approach more general - Metacat generates the datacite documents for DOIs. The DOI plug-ins, e.g. EZID or OSTI, response to transform the datacite document to their own standards, then send them to their servers.

[vchendrix]

@taojing2002 Add a GH action to do the maven build and push the jar to the package registry (maven) as an artifact.