模拟postgresql服务端

v1版本简单实现

1. PgServer启动
2. 客户端连接
3. 输入sql: select * from user;
4. 输出row: <table, user>

官网参考

Specification for all frontend/backend messages: https://www.postgresql.org/docs/14/protocol-message-formats.html
Message Data Types: https://www.postgresql.org/docs/14/protocol-message-types.html