add '--dbg-server' command-line argument & add debugging server draft

src/engine/Engine.hpp

@@ -36,6 +36,7 @@ namespace network {
 
 namespace devtools {
     class Editor;
+    class DebuggingServer;
 }
 
 class initialize_error : public std::runtime_error {
@@ -50,6 +51,7 @@ struct CoreParameters {
     std::filesystem::path userFolder = ".";
     std::filesystem::path scriptFile;
     std::filesystem::path projectFolder;
+    std::string debugServerString;
     int tps = 20;
 };
 
@@ -72,6 +74,7 @@ class Engine : public util::ObjectsKeeper {
     std::unique_ptr<Input> input;
     std::unique_ptr<gui::GUI> gui;
     std::unique_ptr<devtools::Editor> editor;
+    std::unique_ptr<devtools::DebuggingServer> debuggingServer;
     PostRunnables postRunnables;
     Time time;
     OnWorldOpen levelConsumer;