Added AngelScript HTTP request API

[ohlidalp]

Excerpt from new file "contrib/example-script.as":

void main() {
    server.Log("Hello angelscript!");
    
    HttpResponse response = server.httpRequest(
        "GET",                    // Method: GET/POST/PUT/DELETE
        "www.example.com",        // Host
        "/",                      // Server file path
        "text/plain",             // Content type, see https://en.wikipedia.org/wiki/Media_type
        "");                      // Payload
    string logHttp = "HTTP response code: " + response.getCode(); // For text, use `response.getBody()`
    server.Log(logHttp);
}

Outputs:

05-10-2020 14:35:51|t01| INFO|SCRIPT|Hello angelscript!
05-10-2020 14:35:52|t01| INFO|SCRIPT|HTTP response code: 200

[ohlidalp]

Closing - superseded by #160