Add Support for Prepared Statements in LuaSQL

LuaSQL currently does not support prepared statements, which are widely used in modern database applications for performance, security, and efficient query execution. Without this feature, applications must repeatedly send full SQL queries to the database, which prevents query reuse and makes parameter binding difficult. This project will design and implement a minimal and portable prepared statement API for LuaSQL. The API will introduce a new Statement object with methods such as prepare, bind, execute, and close. The design will follow LuaSQL’s existing conventions and ensure that the interface can be implemented consistently across different database drivers. The implementation will focus on the Oracle OCI8 driver as the first complete backend. It will support parameter binding, statement reuse, cursor integration, and proper resource management. Special attention will be given to handling cursor lifecycles and ensuring consistent behaviour across different DBMS APIs. At the end of the project, LuaSQL will include a working prepared statement API, a full OCI8 driver implementation, comprehensive tests, and updated documentation so that other drivers can implement the same interface in the future.