Allow defining only one on-assessment-review-question message at a time

problem_builder/public/css/questionnaire-edit.css

@@ -5,6 +5,13 @@
   line-height: 30px;
 }
 
+.xblock .add-xblock-component .new-component .new-component-type .add-xblock-component-button.disabled,
+.xblock .add-xblock-component .new-component .new-component-type .add-xblock-component-button.disabled:hover {
+  background-color: #ccc;
+  border-color: #888;
+  cursor: default;
+}
+
 .xblock[data-block-type=pb-mcq] .submission-message-help p,
 .xblock[data-block-type=pb-mrq] .submission-message-help p,
 .xblock[data-block-type=pb-rating] .submission-message-help p {

problem_builder/public/js/questionnaire_edit.js

-function QuestionnaireEdit(runtime, element) {
-    'use strict';
-    ProblemBuilderUtil.transformClarifications(element);
-}

problem_builder/questionnaire.py

@@ -181,8 +181,8 @@ class QuestionnaireAbstractBlock(StudioEditableXBlockMixin, StudioContainerXBloc
         fragment.add_css_url(self.runtime.local_resource_url(self, 'public/css/problem-builder.css'))
         fragment.add_css_url(self.runtime.local_resource_url(self, 'public/css/questionnaire-edit.css'))
         fragment.add_javascript_url(self.runtime.local_resource_url(self, 'public/js/util.js'))
-        fragment.add_javascript_url(self.runtime.local_resource_url(self, 'public/js/questionnaire_edit.js'))
-        fragment.initialize_js('QuestionnaireEdit')
+        fragment.add_javascript_url(self.runtime.local_resource_url(self, 'public/js/mentoring_edit.js'))
+        fragment.initialize_js('MentoringEditComponents')
         return fragment
 
     def validate_field_data(self, validation, data):