feat(cli): add command line interface with comprehensive features

Implements a full-featured CLI for Crawl4AI with the following capabilities:
- Basic and advanced web crawling
- Configuration management via YAML/JSON files
- Multiple extraction strategies (CSS, XPath, LLM)
- Content filtering and optimization
- Interactive Q&A capabilities
- Various output formats
- Comprehensive documentation and examples

Also includes:
- Home directory setup for configuration and cache
- Environment variable support for API tokens
- Test suite for CLI functionality

docs/examples/cli/crawler.yml

@@ -0,0 +1,13 @@
+cache_mode: "bypass"
+wait_until: "networkidle"
+page_timeout: 30000
+delay_before_return_html: 0.5
+word_count_threshold: 100
+scan_full_page: true
+scroll_delay: 0.3
+process_iframes: false
+remove_overlay_elements: true
+magic: true
+verbose: true
+exclude_external_links: true
+exclude_social_media_links: true