Table组件showExpandColumn可以增加函数支持吗?

[ty-lq]

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

What problem does this feature solve?

这样我可以根据data-source的每一行的值判断是否需要展示行展开列

What does the proposed API look like?

这是旧版:showExpandColumn="false"
这是新版:showExpandColumn="(record) => record.children && record.children.length > 0"

[webvs2]

请在discussions里面进行讨论，改动会在特点的展开逻辑中修改一些工作，尤其是在懒加载的判断中，不过我认为可以添加，将提供PR