Restructure deep crawling code into a dedicated module with improved organization:
- Move deep crawl logic from async_deep_crawl.py to deep_crawling/
- Create separate files for BFS strategy, filters, and scorers
- Improve code organization and maintainability
- Add optimized implementations for URL filtering and scoring
- Rename DeepCrawlHandler to DeepCrawlDecorator for clarity
BREAKING CHANGE: DeepCrawlStrategy and BreadthFirstSearchStrategy imports need to be updated to new package structure