Added Nextcloud base

lib/data/dataHolder.dart

@@ -1,11 +1,18 @@
 import 'package:flutter/cupertino.dart';
 import 'package:localstore/localstore.dart';
 
+import '../api/apiResponse.dart';
+
 abstract class DataHolder extends ChangeNotifier {
 
   CollectionRef storage(String path) {
     return Localstore.instance.collection(path);
   }
 
-  Future<void> run();
+  void run();
+  List<ApiResponse?> properties();
+
+  bool primaryLoading() {
+    return properties().where((element) => element != null).isEmpty;
+  }
 }