CRUD中配置使用子对象属性后，可以正常显示，但是sortable无效

#### 描述问题：

CRUD中配置使用子对象属性后，可以正常显示，但是sortable无效

```
// 显示正常，且sortable在UI上点击有效
{ "name": "ut", "label": "更新时间", "sortable": true, "type": "date", "format": "YYYY-MM-DD HH:mm:ss" },
// 显示正常，但sortable在UI上点击无效
{ "name": "childData.ut", "label": "更新时间", "sortable": true, "type": "date", "format": "YYYY-MM-DD HH:mm:ss" },
```

amis刚刚今天升级到2.6.0

Start by reproducing the CRUD table behavior with the two configurations shown: compare sorting for `name` with sorting for `childData.ut` after upgrading to amis 2.6.0. Trace the CRUD sorting entry point and determine why the nested property is displayed but not included in the sort request; done means clicking the column sorts by the child object's `ut` value.

Written by the indexing model from the issue text.