TF-1684 Add abstract TransformHtmlSignature method

(cherry picked from commit dfaa5187d1b6a6c1065c65699b6e3a287d1d0843)

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

@@ -0,0 +1,27 @@
+import 'package:core/presentation/state/failure.dart';
+import 'package:core/presentation/state/success.dart';
+
+class TransformHtmlSignatureLoading extends UIState {
+
+  TransformHtmlSignatureLoading();
+
+  @override
+  List<Object?> get props => [];
+}
+
+class TransformHtmlSignatureSuccess extends UIState {
+  final String signature;
+
+  TransformHtmlSignatureSuccess(this.signature);
+
+  @override
+  List<Object?> get props => [signature];
+}
+
+class TransformHtmlSignatureFailure extends FeatureFailure {
+
+  TransformHtmlSignatureFailure(exception) : super(exception: exception);
+
+  @override
+  List<Object?> get props => [exception];
+}