After a first attempt with D7812 this one use a different strategy to
Fetch and extract "core.files.tar.gz", "extra.files.tar.gz" and "community.files.tar.gz" from archives.archlinux.org. That step ensure that we have a list of "official" packages.
Parse metadata from 'desc' file to build origins url.
Scrap the origin url to get artifacts metadata that list all versions of a package.