more progress on custom options config

modules/global/helpers.nix

@@ -0,0 +1,15 @@
+{ inputs, self, ... }: {
+  flake.nixosModules.global = { pkgs, config, lib, ... }: {
+    options.helpers = {
+      mkSymlinkActivationScript = lib.mkOption {
+        type = lib.types.functionTo lib.types.str;
+        default = {target, source, isDir ? false}: ''
+          if [ ${if isDir then "-d" else "-f"} /home/grey/${target} ]; then
+            rm${if isDir then " -rf" else ""} /home/grey/${target}
+          fi
+          ln -s ${config.info.rootPath}/${source} /home/grey/${target}
+        '';
+      };
+    };
+  };
+}