feat[preview]: 增加图文题的支持

- 增加组件 PreviewTextWithImages.vue.
- preview 开放图文题入口

src/views/Design/components/Questions/TextWithImages.vue

@@ -3,7 +3,7 @@
     <van-field
       readonly
       :label="element.stem"
-      :required="element.config.is_required === 1"
+      :required="element.config?.is_required === 1"
       label-align="top"
       class="base-select contenteditable-question-title"
     >