feat(config): initial

Based on `cce47e4df5/standard`
Adds (experimental) support for `nix-on-droid` and `nix-on-darwin`
Includes support for multiple hosts of each base
Adds config for `cheetah` on `nix-on-droid`

pkgs/default.nix

@@ -0,0 +1,6 @@
+# Custom packages, that can be defined similarly to ones from nixpkgs
+# You can build them using 'nix build .#example' or (legacy) 'nix-build -A example'
+
+{ pkgs ? (import ../nixpkgs.nix) { } }: {
+  # example = pkgs.callPackage ./example { };
+}