Can the switcherIcon slot of the tree component return the identifier of whether the current node is expanded?

[shaun931026]

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

What problem does this feature solve?

类似collapse组件的expandIcon slot会返回isActive一样，希望能够根据此标识来决定用什么icon。

What does the proposed API look like?

<template #switcherIcon="{ isExpand }">
  <IconMinus v-if="isExpand" />
  <IconPlus v-if="!isExpand" />
</template>

[linpengteng]

可用 item scopedSlots: { switcherIcon: 'switcherIcon' } 解决