OAI-PMH dc elements

[pdurbin]

This is the new #3378. It's simply me cherry-picking 4d783b3 and making a new branch from the tip of develop. I know it compiles but that's about it. @landreev did some code review already at #3368 (comment)

RFI Checklist

1. Related Issues

• Possible error in oai-pmh xml output file (dc elements namespace and uses) #3368 Possible error in oai-pmh xml output file (dc elements namespace and uses)

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2. Pull Request Checklist

• Functionality completed as described in FRD
• Dependencies, risks, assumptions in FRD addressed
• Unit tests completed
• Deployment requirements identified (e.g., SQL scripts, indexing)
• Documentation completed
• All code checkins completed

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3. Review Checklist

After the pull request has been submitted, fill out this section.

• Code review completed or waived
• Testing requirements completed
• Usability testing completed or waived
• Support testing completed or waived
• Merged with develop branch and resolved conflicts

Made a distinct method for OAI-DC export kind. Related to #3368

connects #3368