TF-4195 Add interactor/repository/datasource to feature add a Label to an email

labels/lib/model/label.dart

@@ -1,8 +1,10 @@
 import 'package:equatable/equatable.dart';
 import 'package:jmap_dart_client/http/converter/id_converter.dart';
 import 'package:jmap_dart_client/jmap/core/id.dart';
+import 'package:jmap_dart_client/jmap/mail/email/keyword_identifier.dart';
 import 'package:json_annotation/json_annotation.dart';
 import 'package:labels/converter/hex_color_nullable_converter.dart';
+import 'package:labels/converter/keyword_identifier_nullable_converter.dart';
 import 'package:labels/model/hex_color.dart';
 
 part 'label.g.dart';
@@ -13,11 +15,12 @@ part 'label.g.dart';
   converters: [
     IdConverter(),
     HexColorNullableConverter(),
+    KeywordIdentifierNullableConverter(),
   ],
 )
 class Label with EquatableMixin {
   final Id? id;
-  final String? keyword;
+  final KeyWordIdentifier? keyword;
   final String? displayName;
   final HexColor? color;