feat(http2): add HTTP/2 support

[Abdel-Monaam-Aouini]

This PR adds native HTTP/2 support to Express, allowing developers to leverage HTTP/2's performance improvements while maintaining Express's familiar API. Features :

1. Complete HTTP/2 integration with both plain and secure (TLS) servers
2. Compatible API with existing Express applications
3. Proper handling of HTTP/2 streams, headers, and request/response objects
4. Comprehensive test suite that verifies all aspects of HTTP/2 functionality
5. Example application demonstrating HTTP/2 usage

[Abdel-Monaam-Aouini]

@wesleytodd any updates here