Proxy support & OS X

[goforit22123-netizen]

Hi, thank you very much for the library!

1. How can I establish a connection to an MQTT server using an HTTP proxy? One option is to pass the client a socket that has already established a connection to the proxy server, but I couldn't find a constructor in boost::mqtt5::mqtt_client::mqtt_client for passing a custom socket.
2. https://www.boost.org/library/latest/mqtt5/ says the library has been tested on Windows and Linux. Do you plan to also include OS X support? After all, boost is a cross-platform library.

Thank you for your attention

[biljazovic]

1. This is techincally possible by providing a custom stream implementation as the StreamType parameter (see MQTT over WebSocket on Emscripten #39). However, it is not without friction, as the library expects the lowest stream layer to inherit asio::ip::tcp::socket. We may improve this area in the future.
2. Library has been tested with Apple Clang 17 on macOS 15, I forgot to update the documentation. Thanks for pointing it out!

[goforit22123-netizen]

@biljazovic

Thanks for your reply!

It would be great if you could add a simple way to use an HTTP proxy, thanks!