OAI-PMH for integrating an existing repository w/ an index

[metasj]

We should have an explicit process for this. Compare Dataverse's approach.

[agnescameron]

Based on some research, the plan for this is to:

• implement OAI-PMH queries using the GetRecord verb for individual records in the index, to get metadata (based on some research this might only be possible for Dataverse records right now, in touch with Zenodo to see if their interface can be used)
• draft a list of repositories with OAI-PMH enabled that might contain datasets of interest
• look into integrating search with OAI-PMH to regularly harvest relevant metadata from these repositories (this could be done either as a weekly Github action or on a separate server entirely)
• investigate becoming a Service Provider (running our own server that provides a metadata index)