Arch Linux loader
Fetch Arch linux packages from lister discovered origins. For each origin it get versions from extra_loader_arguments['artifacts']
Arch Linux package can comes as .xz or .zst file archive. Support for .zst (Zstandard compression) has been requested with swh-core!281 (closed). CI should fail until swh-core!281 (closed) is merged.
Related to T4233
Migrated from D7995 (view on Phabricator)