Create assets_bundle.yml

Created by: hunterk

This recipe compiles the assets into a bundle that is identical to the one on the buildbot server (AFAICT), which is downloaded from the online updater's "update assets" function.

The recipe runs on any push to master or when an owner of the repo stars the repo (as a way to trigger manual builds, which github actions can't do for some reason) and then publishes the bundle to a single 'Latest' tag, overwriting the previous bundle.