Homebrew install/update

[kpgalligan]

The install process is not great. Explore homebrew install.

How to make one is not super clear. Here's a place to start: https://docs.brew.sh/Formula-Cookbook

[TadeasKriz]

I've setup a homebrew-touchlab tap repository in the touchlab org. In there is a single formula for xcode-kotlin.

You can install it using:

brew install --head touchlab/homebrew-touchlab/xcode-kotlin

However the way I did it is kinda hacky, because it seems homebrew shouldn't be used this way. It should leave some artefacts behind, where I just ran setup.sh and then created an empty SUCCESS file so that homebrew thinks everything is alright. I've also set it to keg-only mode where it shouldn't pollute the PATH (with the SUCCESS file).

@kpgalligan Take a look and let me know if this is what you imagined, or you'd like something else. I tried to make it as simple as possible for now and we can improve on that.