Benchmark registries

[mkaput]

Do a quick benchmark of Scarb registry client implementation, to measure a) how does it's HTTP/2 requesting scheme look like and b) how fast it is.

This can be done without deploying Scarbiec. One could make a big local registry, push it to GitHub Pages and use that one as reference. GitHub Pages are hosted behind Cloudfront CDN, which should be a pretty realistic mock of how we plan to deploy Scarbiec to production.