TF-296 Fix download file on browser

lib/features/email/domain/state/download_attachment_for_web_state.dart

@@ -0,0 +1,18 @@
+import 'package:core/core.dart';
+
+class DownloadAttachmentForWebSuccess extends UIState {
+
+  DownloadAttachmentForWebSuccess();
+
+  @override
+  List<Object> get props => [];
+}
+
+class DownloadAttachmentForWebFailure extends FeatureFailure {
+  final exception;
+
+  DownloadAttachmentForWebFailure(this.exception);
+
+  @override
+  List<Object> get props => [exception];
+}