Support MacOS

[devnote-dev]

Crimson does not compile on MacOS/Darwin systems yet. I have virtually no experience with package management on MacOS systems as well as the distribution process for it. From the research I have been able to do, it seems fairly similar to the Linux env implementation so it can probably be reused for MacOS with a few tweaks.

[nobodywasishere]

I think crimson on MacOS should use ~/Library and install per-user instead of globally.
See https://code.whatever.social/questions/3373948/equivalents-of-xdg-config-home-and-xdg-data-home-on-mac-os-x#5084892. I'd be happy to help work on this.

[devnote-dev]

Sounds good, when I last looked at the MacOS implementation it seemed there was no official packaging system, has this changed or will Crimson need to handle Crystal's dependencies manually? At the time I had tried to make things work with Homebrew but because of its cellar system (among other conflicts) it wasn't feasible.

(unrelated: it's been exactly a year since this issue was made, perfect timing 😄)