Feature: Allow custom headers to be passed via WebSocket

[Jeremy-Boyle]

Implement functionality to send and access custom headers during WebSocket handshake and server communication. This enhancement improves authentication and client-server interactions.

Closes: #1342

To Do:

• Update readme with new examples
• Update websocket api to allow optional headers
• Update websocket server to be able to handle headers
  • Implement way to get the headers
• Update Tests
• Update c-api (Can you please help implement this, not sure what would be best here, for the new functions / names)

[paullouisageneau]

It looks good overall, thank you. I just have a few comments, the main one being about introducing two maps whereas it seems to me that one would do the job.

[paullouisageneau]

Nitpick, but since you plan to store the map, you should pass it by value and move it into the WsHandshake() constructor.

[paullouisageneau]

I think you should at least sanitize headerValue:

Suggested change

	for (const auto& [headerName, headerValue] : mCustomHeaders) {
	out += headerName + ": " + headerValue + "\r\n";
	}
	for (auto [headerName, headerValue] : mCustomHeaders) {
	headerValue.erase(std::remove(headerValue.begin(), headerValue.end(), '\r'), headerValue.end());
	std::replace(headerValue.begin(), headerValue.end(), '\n', ' ');
	out += headerName + ": " + headerValue + "\r\n";
	}

[paullouisageneau]

Is there a reason to use two different maps here? You could use only one multimap.

[Jeremy-Boyle]

Hey ! It's to add support for the websocket server.

But good suggestion. Rather than custom and request we can just rename them to request headers or just headers up to you.