Add extra function for lib, and refactor with loadImports

lib/default.nix

@@ -0,0 +1,17 @@
+final: _prev: {
+  youthlic = {
+    loadImports' = dir: f:
+      if (builtins.pathExists dir && (builtins.readFileType dir) == "directory")
+      then
+        with final;
+          pipe dir [
+            builtins.readDir
+            attrNames
+            (filter (name: name != "default.nix"))
+            f
+            (map (name: dir + "/${name}"))
+          ]
+      else [];
+    loadImports = with final; flip youthlic.loadImports' (x: x);
+  };
+}