Enhance CLI with additional options and formatting capabilities

[seantomburke]

This PR enhances the CLI tool with the following improvements:

Features Added

• Added all options from README.md as command-line arguments with both long and short forms
• Added formatting options (--format):
  • plaintext (default): Human-readable output
  • csv: Export URLs as CSV, with fields when specified
  • json: Complete JSON output including errors
• Added output redirection to files with --output flag
• Comprehensive --help command showing all available options
• Version display with --version
• Support for field selection with --fields (includes loc, lastmod, priority, etc.)
• Added exclusion patterns with --exclusions
• All other Sitemapper parameters accessible via CLI

Example Usage

# Basic usage
npx sitemapper https://example.com/sitemap.xml

# With options
npx sitemapper https://example.com/sitemap.xml --format json --timeout 20000

# With field selection and CSV output
npx sitemapper https://example.com/sitemap.xml --fields loc,lastmod,priority --format csv --output results.csv

These improvements make the CLI tool much more useful and consistent with modern CLI standards.