Export compressed PURL catalog list

[DennisClark]

On a periodic basis (to be determined), export a compressed list of PURLs and publish it to be easily integrated into tools as a library.

Deliverable: A compressed list of cataloged PURLs to check if a package, keyed by a PURL, is known to exist, available for on-premises, offline use - includes the release automation.

This builds upon the ongoing work on FederatedCode. This will be automatically created from running PurlDB tools and extracting the PURL list from the PurlDB, and periodically released as a downloadable archive from GitHub for on-premises, offline use.