TF-527 Add domain layer in add new identity

lib/features/manage_account/domain/state/create_new_identity_state.dart

@@ -0,0 +1,21 @@
+import 'package:core/core.dart';
+import 'package:jmap_dart_client/jmap/identities/identity.dart';
+
+class CreateNewIdentitySuccess extends UIState {
+
+  final Identity newIdentity;
+
+  CreateNewIdentitySuccess(this.newIdentity);
+
+  @override
+  List<Object?> get props => [newIdentity];
+}
+
+class CreateNewIdentityFailure extends FeatureFailure {
+  final dynamic exception;
+
+  CreateNewIdentityFailure(this.exception);
+
+  @override
+  List<Object> get props => [exception];
+}