refactor: create MainMenu and GameMenu classes

include/render/gui/MainMenu.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include "GuiWidget.h"
+
+#include "render/gui/imgui/imgui_filebrowser.h"
+
+#include "game/server/Server.h"
+
+#include <memory>
+
+namespace td {
+namespace gui {
+
+class MainMenu : public GuiWidget {
+private:
+    bool m_TriedToConnect = false;
+    bool m_TriedToCreate = false;
+    std::string m_ConnectAddress;
+    int m_ConnectPort;
+    int m_ServerPort = 25565;
+    std::string m_WorldFilePath;
+    imgui_addons::ImGuiFileBrowser m_FileDialog;
+
+    std::unique_ptr<server::Server> m_Server;
+public:
+    MainMenu(client::Client* client);
+    ~MainMenu();
+
+    virtual void render();
+
+    const server::Server* getServer() const { return m_Server.get(); }
+private:
+    bool startServer();
+};
+
+} // namespace gui
+} // namespace td