Upgrade HTTP parser from http-parser to llhttp. v7.0.77

[winlinvip]

This PR modernizes SRS's HTTP handling by upgrading from the legacy http-parser library to the more performant and actively maintained llhttp library.

• Replace http-parser with llhttp: Migrated from the deprecated http-parser to llhttp for better performance and maintenance
• API compatibility: Updated all HTTP parsing logic to use llhttp APIs while maintaining backward compatibility
• Simplified URL parsing: Replaced complex http-parser URL parsing with custom simple parser implementation
  Enhanced error handling: Improved error reporting with llhttp's better error context and positioning