NPOI 设置合并区域的边框
参考资料：https://blog.csdn.net/keenrob/article/details/102953239
1 RegionUtil.SetBorderLeft(1, region, sheet, workbook)//左 2 RegionUtil.SetBorderRight(1, region, sheet, workbook)//右 3 RegionUtil.SetBorderTop(1, region, sheet, workbook)//顶 4 RegionUtil.SetBorderBottom(1, region, sheet, workbook)//底
