[slick-net] new port

[freshthinking]

If this PR adds a new port, please uncomment and fill out this checklist:

• Changes comply with the maintainer guide.
• The name of the port matches an existing name for this component on https://repology.org/ if possible, and/or is strongly associated with that component on search engines.
• Optional dependencies are resolved in exactly one way. For example, if the component is built with CMake, all find_package calls are REQUIRED, are satisfied by vcpkg.json's declared dependencies, or disabled with CMAKE_DISABLE_FIND_PACKAGE_Xxx.
• The versioning scheme in vcpkg.json matches what upstream says.
• The license declaration in vcpkg.json matches what upstream says.
• The installed as the "copyright" file matches what upstream says.
• The source code of the component installed comes from an authoritative source.
• The generated "usage text" is accurate. See adding-usage for context.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is in the new port's versions file.
• Only one version is added to each modified port's versions file.

Description:
Add new port for slick-net, a high-performance C++ HTTP/WebSocket client library built on Boost.Beast with full SSL/TLS support. Designed for asynchronous, non-blocking HTTP/WebSocket communication in modern C++ applications.

Features:

• HTTP/HTTPS Client: Full support for GET, POST, PUT, PATCH, and DELETE methods
• HTTP Streaming: Support for Server-Sent Events (SSE) and chunked response streaming
• Asynchronous WebSocket Client: Built on Boost.Asio coroutines for high-performance async operations
• SSL/TLS Support: Native support for secure https:// and wss:// connections
• Multiple Async APIs: Synchronous, callback-based, and C++20 coroutine awaitable interfaces
• Cross-Platform: Works on Windows, Linux, and macOS
• Header-Only: Easy integration with minimal dependencies
• Callback-Based API: Clean event-driven interface for connection lifecycle management
• Thread-Safe: Proper strand management for concurrent operations
• Modern C++20: Leverages coroutines and modern C++ features

Homepage: https://github.com/SlickQuant/slick_net
License: MIT

[vicroms]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[vicroms]

Please remove the version>= constraints on the package dependencies.

D:\a\_work\1\s\ports\slick-net\vcpkg.json: error: the "version>=" constraint to openssl names version 3.0.0 which does not exist in the version database. All versions must exist in the version database to be interpreted by vcpkg.

[freshthinking]

Thanks, I pushed the fix.