TF-1311: set subscribeMailbox in UseCase and implement in Repository

lib/features/mailbox/domain/model/subscribe_mailbox_request.dart

@@ -0,0 +1,14 @@
+import 'package:equatable/equatable.dart';
+import 'package:jmap_dart_client/jmap/mail/mailbox/mailbox.dart';
+import 'package:tmail_ui_user/features/mailbox/domain/model/mailbox_subscribe_state.dart';
+
+class SubscribeMailboxRequest with EquatableMixin {
+
+  final MailboxId mailboxId;
+  final MailboxSubscribeState newState;
+
+  SubscribeMailboxRequest(this.mailboxId, this.newState);
+  
+  @override
+  List<Object?> get props => [mailboxId, newState];
+}