Refactor codebase resolving warnings and remove self-package imports

lib/model/files/filesProps.dart

@@ -0,0 +1,54 @@
+
+import '../../api/apiResponse.dart';
+import '../../api/marianumcloud/webdav/queries/listFiles/listFilesCache.dart';
+import '../../api/marianumcloud/webdav/queries/listFiles/listFilesResponse.dart';
+import '../dataHolder.dart';
+
+extension ExtendedList on List {
+  T indexOrNull<T>(int index) =>  index +1 <= length ? this[index] : null;
+  T firstOrNull<T>() => isEmpty ? null : first;
+  T lastOrNull<T>() => isEmpty ? null : last;
+}
+
+class FilesProps extends DataHolder {
+  List<String> folderPath = List<String>.empty(growable: true);
+  String currentFolderName = "Home";
+
+  ListFilesResponse? _listFilesResponse;
+  ListFilesResponse get listFilesResponse => _listFilesResponse!;
+
+  void runPath(List<String> path) {
+    folderPath = path;
+    run();
+  }
+
+  @override
+  List<ApiResponse?> properties() {
+    return [_listFilesResponse];
+  }
+
+  @override
+  void run() {
+    _listFilesResponse = null;
+    notifyListeners();
+    ListFilesCache(
+      path: folderPath.isEmpty ? "/" : folderPath.join("/"),
+      onUpdate: (ListFilesResponse data) => {
+        _listFilesResponse = data,
+        notifyListeners(),
+      }
+    );
+  }
+
+  void enterFolder(String name) {
+    folderPath.add(name);
+    currentFolderName = name;
+    run();
+  }
+
+  void popFolder() {
+    folderPath.removeLast();
+    if(folderPath.isEmpty) currentFolderName = "Home";
+    run();
+  }
+}