TF-2644 Display warning dialog when pick file exceeded maximum size in composer

lib/features/upload/domain/extensions/list_file_info_extension.dart

@@ -0,0 +1,7 @@
+import 'package:model/upload/file_info.dart';
+
+extension ListFileInfoExtension on List<FileInfo> {
+  List<int> get listSize => map((file) => file.fileSize).toList();
+
+  num get totalSize => listSize.reduce((sum, size) => sum + size);
+}