Add homebrew and scoop for easier non-JS installation

[garethr]

As well as having npm installation, it would be great to have other options for folks not wanting to manage source installs.

For inspiration, at SNyk we use pkg to create an all-in-one installation of Snyk, which packages Node and the Snyk CLI. It's easy to set up and use in an automated fashion https://github.com/vercel/pkg#readme

Once you have a standalone version, Homebrew and Scoop are simple enough to set up. The follow repositories are hands off, and use the GitHub API and GitHub Actions to periodically release new versions for those platforms.

https://github.com/snyk/homebrew-tap
https://github.com/snyk/scoop-snyk