Refactor Kuloy to call CouloyDB's transaction interface for operations.

[bigboss2063]

The original Kuloy implemented data structures and supported commands at the server level. However, now that the storage engine layer (CouloyDB) natively supports data structures, it requires modification to utilize the interfaces provided by the storage engine layer for command implementation.

原本的 Kuloy 实现数据结构以及支持命令的方式是在 Server 层进行实现的，而现在存储引擎层（CouloyDB）已经原生支持数据结构，所以需要进行更改，用存储引擎层提供的接口来实现命令。