TF-527 Add domain layer in add new identity

lib/features/manage_account/domain/model/create_new_identity_request.dart

@@ -0,0 +1,15 @@
+
+import 'package:equatable/equatable.dart';
+import 'package:jmap_dart_client/jmap/core/id.dart';
+import 'package:jmap_dart_client/jmap/identities/identity.dart';
+
+class CreateNewIdentityRequest with EquatableMixin {
+
+  final Identity newIdentity;
+  final Id creationId;
+
+  CreateNewIdentityRequest(this.creationId, this.newIdentity);
+
+  @override
+  List<Object?> get props => [creationId, newIdentity];
+}