TF-3449 Display mark as important icon in email list

Signed-off-by: dab246 <tdvu@linagora.com>

lib/features/composer/presentation/model/mail_priority_header.dart

@@ -1,27 +0,0 @@
-
-import 'package:equatable/equatable.dart';
-
-class MailPriorityHeader with EquatableMixin {
-  final String? xPriority;
-  final String? importance;
-  final String? priority;
-
-  MailPriorityHeader({
-    this.xPriority,
-    this.importance,
-    this.priority,
-  });
-
-  factory MailPriorityHeader.asImportant() => MailPriorityHeader(
-    xPriority: '1',
-    importance: 'high',
-    priority: 'urgent',
-  );
-
-  @override
-  List<Object?> get props => [
-    xPriority,
-    importance,
-    priority,
-  ];
-}