Refactor: Split exception classes into separate files

[chrmarek]

Split PDO_DataObject_Exception child classes from Exception.php into individual files in PDO/DataObject/Exception/ directory:

• InvalidArgs.php
• NoData.php
• InvalidConfig.php
• NoClass.php
• Set.php
• Connect.php
• Query.php

Each child class now has its own file while maintaining the same class names and namespace structure. The base Exception.php file loads all child classes via require_once to maintain backward compatibility with existing code that uses the factory pattern.

This improves code organization and makes individual exception classes easier to locate and maintain.

Thix fixes the issue where phpstan complains about not finding sub exception classes.