table 树形表格组件 如何设置当前展开的项

[huicunjun]

• I have searched the issues of this repository and believe that this is not a duplicate.

What problem does this feature solve?

需要实现功能 一键展开/折叠所有
文档没找到相应case

What does the proposed API look like?

需要实现功能 一键展开/折叠所有
文档没找到相应case

[webvs2]