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`

overlays/default.nix

@@ -0,0 +1,14 @@
+# This file defines overlays
+{
+  # This one brings our custom packages from the 'pkgs' directory
+  additions = final: _prev: import ../pkgs { pkgs = final; };
+
+  # This one contains whatever you want to overlay
+  # You can change versions, add patches, set compilation flags, anything really.
+  # https://nixos.wiki/wiki/Overlays
+  modifications = final: prev: {
+    # example = prev.example.overrideAttrs (oldAttrs: rec {
+    # ...
+    # });
+  };
+}