Core: Add StateMachine

Backported from legacy Nazara

src/Nazara/Core/State.cpp

@@ -0,0 +1,17 @@
+// Copyright (C) 2023 Jérôme "Lynix" Leclercq (lynix680@gmail.com)
+// This file is part of the "Nazara Engine - Core module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#include <Nazara/Core/State.hpp>
+#include <Nazara/Core/Debug.hpp>
+
+namespace Nz
+{
+	/*!
+	* \ingroup Core
+	* \class Nz::State
+	* \brief Core class that represents a state of your application
+	*/
+
+	State::~State() = default;
+}