Massive refactoring into module-based approach

modules/hardware/hibernate.nix

@@ -0,0 +1,23 @@
+{ config, lib, ... }:
+let
+  cfg = config.custom.hibernate;
+in
+{
+  options.custom.hibernate.enable = lib.mkOption {
+    type = lib.types.bool;
+    default = false;
+  };
+
+  config = lib.mkIf cfg.enable {
+    swapDevices = [
+      {
+        device = "/var/lib/swapfile";
+        size = 16 * 1024;
+      }
+    ];
+
+    boot = {
+      resumeDevice = lib.mkDefault "/dev/mapper/nixos";
+    };
+  };
+}