feat(function): get selected tree node (#1857)

chengj

2022-04-29 5ad93c6004026489bd22b32ef049f7c63efc1024

 src/components/Tree/src/Tree.vue

@@ -119,6 +119,7 @@
        getAllKeys,
        getChildrenKeys,
        getEnabledKeys,
        getSelectedNode,
      } = useTree(treeDataRef, getFieldNames);

      function getIcon(params: Recordable, icon?: string) {
@@ -320,6 +321,7 @@
        insertNodesByKey,
        deleteNodeByKey,
        updateNodeByKey,
        getSelectedNode,
        checkAll,
        expandAll,
        filterByLevel: (level: number) => {