feat: Integrate new webserver (#1722)

For #919.
The new web server is not using dosguard yet. It will be fixed by a
separate PR.

src/web/interface/Concepts.hpp

@@ -19,8 +19,6 @@
 
 #pragma once
 
-#include "web/interface/ConnectionBase.hpp"
-
 #include <boost/beast.hpp>
 #include <boost/beast/core/error.hpp>
 
@@ -29,6 +27,8 @@
 
 namespace web {
 
+struct ConnectionBase;
+
 /**
  * @brief Specifies the requirements a Webserver handler must fulfill.
  */