增加对mysql的caching_sha2_password认证插件fullauth流程支持

[bygaoyuan]

环境描述：
MYSQL服务端版本：8.0.30
Canal:1.1.6
关联Issues: #1700
背景：采用caching_sha2_password插件认证，客户端首次连接MySQL服务端/在MYSQL服务端执行flush privileges;，报caching_sha2_password Auth failed。非首次连接则可以正常认证。
复现情况：稳定复现
原因：
从 MySQL 8.0.4 开始，MySQL 默认身份验证插件从 mysql_native_password 改为 caching_sha2_password。
Canal目前支持了caching_sha2_password插件Fast auth功能。
相关commit为：b95c0d03cf42e8637b72b7f2d2dbfab894bef1aa
非首次连接可以正常认证的原因为触发了caching_sha2_password的Fast Auth功能。
本次代码新增了caching_sha2_password的Full Auth功能中从服务端获取public key，然后进行Auth逻辑。实现了在使用caching_sha2_password插件下Canal可以正常连接MYSQL的功能。
相关文档：https://dev.mysql.com/doc/dev/mysql-server/latest/page_caching_sha2_authentication_exchanges.html
单元测试：
执行了com/alibaba/otter/canal/parse/driver/mysql/MysqlConnectorTest.java

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