TF-784 Add SuggestionEmailAddress to separate the state of suggestion

lib/features/composer/presentation/widgets/suggestion_email_address.dart

@@ -0,0 +1,17 @@
+import 'package:equatable/equatable.dart';
+import 'package:jmap_dart_client/jmap/mail/email/email_address.dart';
+
+class SuggestionEmailAddress with EquatableMixin {
+  final EmailAddress emailAddress;
+  final SuggestionEmailState state;
+
+  SuggestionEmailAddress(this.emailAddress, {this.state = SuggestionEmailState.valid});
+
+  @override
+  List<Object?> get props => [emailAddress, state];
+}
+
+enum SuggestionEmailState {
+  valid,
+  duplicated,
+}