Tree 节点设置iconify的图标后样式有待优化

[tky753]

Subject of the feature

建议加一个demo，展示如何设置tree节点的icon

Problem

Tree 节点设置iconify的图标后，发现两个样式问题

import { Icon } from '/@/components/Icon';
......
treeItem.icon = h(Icon, { icon: 'ic:baseline-calendar-view-month', });

1. icon偏下
2. action item 溢出