fix: descriptions not render fragmet children

[ununian]

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[中文版模板 / Chinese template]

This is a ...

• Bug fix

What's the background?

#2793

2. Chinese description (optional)

v-for 在 vue 3 中渲染为 Fragment，在 Descriptions 获取 children 的时候增加 isFragment 判断，并用 flatMap 组合起来

<template>
  <div>
    <a-descriptions title="User Info" bordered :column="2">
      <a-descriptions-item label="test">
        test
      </a-descriptions-item>
      <a-descriptions-item v-for="(prop, index) in vals" :key="index" :label="prop.name">
        {{ prop.type }}
      </a-descriptions-item>
    </a-descriptions>
    <div v-for="(prop, index) in vals" :key="index">
      {{ prop.type }}
    </div>
  </div>
</template>
<script>
export default {
  data() {
    return {
      vals: [
        { id: 1, name: 'prop1', type: 'text' },
        { id: 2, name: 'prop2', type: 'text' },
      ],
    };
  },
};
</script>

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[tangjinzhou]

b616823

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