feat: Add redirect support, client certificate support, HTTP/2 support, and built-in middleware

[CodeyCoo]

Pull Request Description

This Pull Request introduces new features including redirect support, client certificate support, HTTP/2 support, and built-in middleware for headers, cookies, and caching.

Redirect Support:

• Added automatic handling of HTTP redirects (e.g., 301, 302).
• Configurable maximum redirect count and cross-origin redirect support.

Client Certificate Support:

• Added support for loading and using client certificates (cert.pem and key.pem).
• Provided SetCertificates method to configure client certificates.

HTTP/2 Support:

• Enabled HTTP/2 by default.
• Added fallback compatibility with HTTP/1.1.

Built-in Middleware:

• Added Header, Cookie, and Cache middleware.
• Header middleware: Supports custom request headers.
• Cookie middleware: Automatically manages cookies.
• Cache middleware: Implements request caching to reduce redundant requests.

Documentation Updates:

• Added detailed documentation for the new features.
• Provided example code and configuration guides.

Changes

New Files:

• middleware/header.go: Header middleware implementation.
• middleware/cookie.go: Cookie middleware implementation.
• middleware/cache.go: Cache middleware implementation.
• docs/redirect.md: Redirect feature documentation.
• docs/client_certificates.md: Client certificate support documentation.
• docs/http2.md: HTTP/2 support documentation.
• docs/middleware.md: Middleware usage documentation.

Modified Files:

• client.go: Added redirect, client certificate, and HTTP/2 support.
• config.go: Added new configuration options.
• README.md: Updated feature list and quickstart examples.

Testing

• Redirect functionality tests.
• Client certificate support tests.
• HTTP/2 protocol tests.
• Middleware functionality tests (Header, Cookie, Cache).

Impact

• This change is backward-compatible.
• New features are optional and do not affect existing behavior.