Add brotli.js library

Summary: Brotli is a compression algorithm from Google that has similar performance and better compression than Zlib. I'm going to use it in the following diff to compress keyserver -> client socket messages.

Test Plan: Tested in combination with the following diff

Reviewers: atul, michal, kamil

Reviewed By: atul

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D9293