FEAT: Integrate python <->C++ flow with C++ connection class

[gargsaumya]

This pull request makes the database connection and cursor handling in the mssql_python module via new C++ Connection class and simplifying the Python-side implementation. The changes include replacing low-level connection management with a higher-level abstraction, removing redundant methods, and delegating key operations to the new C++ backend. Below are the most important changes grouped by theme:

Refactoring Python Connection Management

• Replaced manual handle allocation (henv, hdbc) and initialization in mssql_python/connection.py with a new Connection class from the C++ backend. The _initializer, _allocate_environment_handle, _allocate_connection_handle, and related methods were removed.
• Simplified transaction methods (commit, rollback) and connection lifecycle methods (close) by delegating their logic to the C++ Connection class.
• Updated autocommit handling to use the set_autocommit and get_autocommit methods from the C++ Connection class.

Refactoring Python Cursor Management

• Removed checks for closed connections in mssql_python/cursor.py and delegated statement handle allocation to the C++ Connection class.
• Simplified cursor cleanup by removing explicit handle freeing logic.

Integration with Python Bindings

• Updated ddbc_bindings.cpp to include the new Connection class, enabling its use in the Python layer.

---

Checklist

• Tests Passed (if applicable) : Pytests need to be fixed with connection logic in C++.

[Copilot]

Pull Request Overview

Adds a new C++ backend for ODBC handle management and switches the Python modules to use it instead of manual handle calls. Major changes include:

• Introducing ddbc_bindings.h and associated C++ classes (DriverLoader, SqlHandle, Connection) to centralize and RAII-manage ODBC API calls.
• Updating Python’s connection.py and cursor.py to delegate operations to the new C++ Connection and SqlHandle bindings.
• Removing legacy Python initialization, handle allocation/free logic, and replacing it with calls into the C++ layer.

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
mssql_python/pybind/ddbc_bindings.h	Added ODBC typedefs, function pointers, DriverLoader, SqlHandle
mssql_python/pybind/connection/connection.h	Defined C++ Connection class and methods
mssql_python/pybind/connection/connection.cpp	Implemented C++ Connection member functions
mssql_python/cursor.py	Removed manual handle allocation/free; uses C++ bindings
mssql_python/connection.py	Replaced Python handle management with C++ Connection

Comments suppressed due to low confidence (4)

mssql_python/pybind/ddbc_bindings.h:4

• Typo in comment: 'is file' should be 'this file'.

// INFO|TODO - Note that is file is Windows specific right now. Making it arch agnostic will be

mssql_python/pybind/connection/connection.h:28

• [nitpick] The member _conn is unused within the C++ Connection class and creates a circular reference; consider removing it.

    std::shared_ptr<Connection> _conn; 

mssql_python/connection.py:168

• self._conn.commit() calls a method that isn't defined in the C++ Connection class. Implement a commit() wrapper (calling end_transaction(SQL_COMMIT)) or update Python to use end_transaction directly.

        self._conn.commit()

mssql_python/connection.py:184

• self._conn.rollback() references a non-existent C++ method. Provide a rollback() wrapper (calling end_transaction(SQL_ROLLBACK)) or adjust Python to use the end_transaction API.

        self._conn.rollback()