By using a single equality instead of checking len() then zip()
to check one by one, pytest can find the common/missing elements
and print them nicely when the two lists are unequal.
Previously we had as many origins as version for a crate package, url was a link
to a specific crate version package.
Refactor to have one origin per package name and add an 'artifacts' entry to
extra_loader_arguments that list all versions, package url and checksum.
Origin url is now a link to the related http api endpoint for a package name.
Related to T4104
The Crates lister retrieves crates package for Rust lang.
It basically fetches https://github.com/rust-lang/crates.io-index.git
to a temp directory and then walks through each file to get the
crate's info.
