refactor: moved common system options to their own file

modules/common.nix

@@ -0,0 +1,40 @@
+# Contains common configration for all machines
+
+{
+  boot.loader.systemd-boot.enable = true;
+  boot.loader.efi.canTouchEfiVariables = true;
+
+  # Set your time zone.
+  time.timeZone = "Asia/Singapore";
+
+  # Select internationalisation properties.
+  i18n.defaultLocale = "en_SG.UTF-8";
+
+  i18n.extraLocaleSettings = {
+    LC_ADDRESS = "en_SG.UTF-8";
+    LC_IDENTIFICATION = "en_SG.UTF-8";
+    LC_MEASUREMENT = "en_SG.UTF-8";
+    LC_MONETARY = "en_SG.UTF-8";
+    LC_NAME = "en_SG.UTF-8";
+    LC_NUMERIC = "en_SG.UTF-8";
+    LC_PAPER = "en_SG.UTF-8";
+    LC_TELEPHONE = "en_SG.UTF-8";
+    LC_TIME = "en_SG.UTF-8";
+  };
+
+  # Configure keymap in X11
+  services.xserver.xkb = {
+    layout = "us";
+    variant = "";
+  };
+
+  # Define a user account. Don't forget to set a password with ‘passwd’.
+  users.users.rafiq = {
+    isNormalUser = true;
+    description = "rafiq";
+    extraGroups = [ "networkmanager" "wheel" ];
+  };
+
+  # Allow unfree packages
+  nixpkgs.config.allowUnfree = true;
+}