TF-3450 Add text attachment preview

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

@@ -0,0 +1,31 @@
+import 'dart:typed_data';
+
+import 'package:core/presentation/state/failure.dart';
+import 'package:core/presentation/state/success.dart';
+import 'package:model/email/attachment.dart';
+
+class GettingTextDataFromAttachment extends LoadingState {
+  GettingTextDataFromAttachment({required this.attachment});
+
+  final Attachment attachment;
+
+  @override
+  List<Object> get props => [attachment];
+}
+
+class GetTextDataFromAttachmentSuccess extends UIState {
+  GetTextDataFromAttachmentSuccess({
+    required this.attachment,
+    required this.data,
+  });
+
+  final Attachment attachment;
+  final Uint8List data;
+
+  @override
+  List<Object> get props => [attachment, data];
+}
+
+class GetTextDataFromAttachmentFailure extends FeatureFailure {
+  GetTextDataFromAttachmentFailure({super.exception});
+}