refactor(pptx): consolidate and enhance PPTX extraction logic

- Refactored the extraction methods across various PPTX extractor classes to improve consistency and efficiency.
- Updated method signatures to include DocumentMeta and return lists of TextElement for better data handling.
- Removed unused methods and streamlined the extraction process for text, hyperlinks, and speaker notes.
- Introduced new extractor classes for metadata and images, enhancing the overall functionality of the PPTX parsing module.
- Updated DEFAULT_EXTRACTORS to reflect the new structure and removed deprecated classes.

Author: maxpill