add brew & scoop setup

[svix-frank]

Okay @tasn I lied, both the brew and scoop need to live in separate repos, I propose two repos: homebrew-svix and scoop-svix

The Homebrew flow can then look like this

brew tap svixhq/svix
brew install svix
# or
brew install svixhq/svix/svix

and the scoop flow will look like this:

scoop bucket add svix https://github.com/svixhq/scoop-svix.git
scoop install svix

Additionally before I can merge this, I need to get setup with access to secrets for this repo as well as write access to the newly created repos.

Closes #1.

[tasn]

I don't understand how this works. Shouldn't owner be svixhq? Does this even work? :P