NestedSelect 级联选择器提交时，可以将父子节点分成多个字段提交吗

我想实现类似级联选择器的功能，先选A，再选A下面的B。

看文档现在级联选择器的父子节点在提交时，数据只存在一个字段中。

不同层级的节点能不能拆成多个字段提交，例如：
```json
{
"type": "nested-select",
"name": "nestedSelect",
"label": "级联选择器",
"options": [
{
"label": "A",
"value": "a"
"children": [
{
"label": "B-1",
"value": "b-1"
}
]
},
{
"label": "C",
"value": "c"
}
]
}
```
期望提交的时候的数据是：
```json
{
"A": "a",
"B": "b-1"
}
```

Start with the NestedSelect documentation and the component's current submission behavior. Trace how parent and child values are serialized, then define how each selected level should map to a separate field. Done means a nested selection submits distinct fields for the selected levels, including the A/B example described in the issue.

Written by the indexing model from the issue text.