Add on-the-fly conflation

[gaurav]

Add the ability to conflate identifiers on the fly.

WIP

• This currently takes 30s for GeneProtein and 60ms for DrugChemical, but we should be able to speed this up quite a bit by downloading the Gzip file instead.
• In case we can't access stars.renci.org, we should keep a copy of the conflation files in the Docker image.
  • This means we should also store the Biolink Model version.
  • We could potentially store the conflation files in the Helm chart somewhere, but that seems... annoying.