feat(Sku): sku supports message initialization (#5668)

src/sku/demo/index.vue

@@ -198,6 +198,9 @@ export default {
         },
       },
       messageConfig: {
+        initialMessages: {
+          留言1: '商品留言',
+        },
         uploadImg: (file, img) =>
           new Promise(resolve => {
             setTimeout(() => resolve(img), 1000);