Summary: Closes https://github.com/facebook/flipper/issues/2578 Adds Brotli compression support for br-encoded endpoints ## Changelog - Brotli compression support Pull Request resolved: https://github.com/facebook/flipper/pull/4288 Test Plan: Confirmed `content-encoding` had `br` for Brotli and that the response text post-decompression was parsed properly:   A note for reviewer(s) is that I am by no means a javascript/typescript/yarn/npm/electron/etc developer, so please please make sure I did things properly and let me know what to fix, how, why it's wrong. Thanks! Reviewed By: antonk52 Differential Revision: D41444623 Pulled By: mweststrate fbshipit-source-id: ac4e84b4501c67a4b89163c20c63de1be14d6cef