Transfer: Support asynchronous data search

[Emiya0306]

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[jikkai]

要是方便的话可以补一下 en-US 和 es 的文档、 d.ts 相关定义以及测试用例

不过这个功能我们可能先要评估下 😓

[Emiya0306]

好的

[ziyoung]

ref #12157
如果仅仅是过滤一些信息的话，就可以 filter-method 中处理了。不太明白这个钩子的用途。

[Emiya0306]

@ziyoung filter-method是个很棒的想法，我曾经也尝试过。不过这个需求点在于实现异步数据获取之后进行过滤。即在filter-input中输入的query作为依据，然后从后端获取数据，作为transfer的渲染数据，来进行过滤。

之前有尝试，由于filter-method是一个同步的方法。如果改造成支持异步，开发者要写很多负担性的代码，比如check当前item是不是第一个未选项，比如check当前输入的query等不等于上一次query(在filter-method修改transfer data会造成渲染死循环)等。

介于上面因素的考虑，我觉得增加一个before-query的属性会更有扩展性，开发者的操作空间也会更大。

[huanz]

求Merge

1. filter-method 无法修改数据
2. 无data filter-method 不触发
3. 左侧数据量可能会比较大的情况，可能需要用户输入关键词搜索出结果，然后再进行操作

[tng10]

@Emiya0306 @huanz I have the same issue here... Did you guys managed to find a workaround without this PR?

@ziyoung what do you think about this PR? Can you merge it?

[ziyoung]

@Emiya0306 先解决一下冲突。

[Emiya0306]

@ziyoung
Done. Sorry for long time no processing, please have a check.
I just add zh-cn and en-us document.

[stale]

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[Emiya0306]

@cs1707 Hey, can anyone check this PR?

[cs1707]

这边初步设想了一下，添加一个 search 事件，可能会是个更好的方式。