Add option to use original fullscreen code for vulkan

lib/graphics_engine/include/ge_main.hpp

@@ -16,6 +16,7 @@ struct GEConfig
 bool m_disable_npot_texture;
 bool m_convert_irrlicht_mesh;
 bool m_texture_compression;
+bool m_vulkan_fullscreen_desktop;
 std::unordered_set<std::string> m_ondemand_load_texture_paths;
 float m_render_scale;
 };