Investigate simplifying PDOConnection to use built-in Doctrine DBAL Connection

## Context

In PR #122, @seut observed that the current `PDOConnection` implementation may be using an old abstraction layer. When reviewing shipped Doctrine DBAL implementations, they noted that these typically only implement the `Driver` class and use the built-in [Connection](https://github.com/doctrine/dbal/blob/3.10.x/src/Driver/PDO/Connection.php) from Doctrine DBAL.

## Task

Investigate whether the custom `PDOConnection` class in `src/Crate/DBAL/Driver/PDOCrate/PDOConnection.php` can be simplified or replaced by leveraging Doctrine DBAL's built-in Connection implementation, similar to how other DBAL drivers are structured.

## References

- PR: https://github.com/crate/crate-dbal/pull/122
- Comment thread: https://github.com/crate/crate-dbal/pull/122#discussion_r2541563710
- Requested by: @amotl

This investigation is intended for a future iteration after PR #122 is completed.