spike: change regex engine

[stefanhengl]

Regex dominates our CPU profiles for webserver. The top 10% profiles are almost exclusively regex. Changing from Go's engine to something faster would have big impact on the critical path.

Inspiration:
https://github.com/BurntSushi/rure-go

[keegancsmith]

Here are notes I took from when we last looked into rure-go (2020-10-21)

This has deployment / devenv issues since rure is written in rust. Requires
compiling rust. Maybe there is a nice way to distribute static objects to link
against in cgo.

[gogo2464]

@stefanhengl @keegancsmith seems right... rust deps is not a plus to build. We could still change for rust to go bindings.