参考：博客园：apisix基于username和password的JWT验证插件
实现
Lua 脚本
-- Licensed to the Apache Software Foundation (ASF) under one or more
-- contributor license agreements. See the NOTICE file distributed with
-- this work for additional information regarding copyright ownership.
-- The ASF licenses this file to You under the Apache License, Version 2.0
-- (the License); you may not use this file except in