Add support for Codspeed performance testing

[bifurcation]

No description provided.

[tarcieri]

Haven't heard of this before but it looks interesting

[tarcieri]

@bifurcation something else that might be interesting is cargo-checkct: https://www.ledger.com/blog-cargo-checkct-our-home-made-tool-guarding-against-timing-attacks-is-now-open-source

[newpavlov]

This will compile cargo-codspeed on each CI run, which is really inefficient. It's better to use pre-compiled releases, e.g. see how we handle cargo-hack installation.

[bifurcation]

Thanks, will try to get things working and then optimize :)

[bifurcation]

@tarcieri Sorry, should have marked this as draft! I'm just playing around with it at this point. I don't think the current rev even works. (Note that there are no real CI checks, since I broke the YAML file.) Probably best to revert until this is debugged.

[tarcieri]

Opened #21 to revert (the GitHub UI for YAML parse failures is awkwardly deceptive, unfortunately)