feat(systemModules:host): add initial host configuration module

used to define general host configuration, including:

- hardware
- name
- admin
- type
- role

system/modules/host/function/default.nix

@@ -0,0 +1,19 @@
+{ lib, ... }:
+
+let
+  inherit (lib) types mkOption;
+in
+
+{
+  imports = [
+    ./gaming
+    ./workstation
+    ./media-server
+  ];
+
+  options.systemModules.host.function = mkOption {
+    type = with types; listOf (enum ["gaming" "workstation" "media-server"]);
+    default = [];
+    description = "Host's primary function/s";
+  };
+}