Instead of querying the metacpan distribution endpoint to list origins,
prefer to use the release endpoint instead enabling to list all artifacts
associated to CPAN packages by scrolling results.
Compared to previous implementation, it enables to compute a last_update
date for all CPAN packages but also to obtain artifact sha256 checksums
that will be used by the CPAN loader to check downloads integrity.
It also enables to save a call to metacapan Web API in cpan loader as all
needed info about package artifacts are now provided as extra loader
arguments.
Related to T2833
When testing this in docker, I could list all CPAN packages and their
artifacts in less than 10 minutes.