Feature: Add brew-nix for fully nix managed homebrew packages

[freitagdavid]

I ran across a cool package that actually converts brew packages to nix managed packages on the fly. I'm still very much a nix amateur but I've mostly managed to get it integrated, only missing thing I can tell is that I can't search the applications I install with spotlight.

I think this would be a solid change to this config so that it's a bit more nix managed. Just wanted to mention this since I saw it and thought it would be useful here.

If you decide against this change, one thing I would still like to inquire, how would I go about making spotlight find these applications? They have links that get placed in the nix repo and gets linked in the Home directory as Home Manager Apps, they are available in Launch Pad but they just don't seem to be searchable with spotlight, haven't been able to figure out how to get them displayed there.

Here's the package I'm referencing: https://github.com/BatteredBunny/brew-nix