参数:
要编码的字符串
返回: 编码后的字符串
例子:
<!--{ffwbms_func urlencode,aa,"https://www.ffwish.com/prod.html?prodname=飞鸿授权码"}-->
<!--{ffwbms_see $aa}-->
返回：
https%3A%2F%2Fwww.ffwish.com%2Fprod.html%3Fprodname%3D%E9%A3%9E%E9%B8%BF%E6%8E%88%E6%9D%83%E7%A0%81
