What problem does this feature solve?

组件：<Tree.DirectoryTree multiple />
问题：当前只支持拖拽单个节点.
需求：支持拖拽多个选中的节点

What does the proposed API look like?

1.当前onDrop的类型为: function({event, node, dragNode, dragNodesKeys})
2.期望更改后的onDrop类型为：
function({event, node, dragNodes, dragNodesKeys})
其中：
dragNodes的值类似：[{key: '1', title: 'node1'}, {key: '2', title: 'node2'}]
dragNodesKeys的值类似：['1', '2']