Reorganize source files into logical subdirectories

Co-authored-by: Hirek193 <23196899+Hirek193@users.noreply.github.com>

rendering/nullrenderer.cpp

@@ -0,0 +1,9 @@
+#include "stdafx.h"
+#include "nullrenderer.h"
+
+std::unique_ptr<gfx_renderer> null_renderer::create_func()
+{
+    return std::unique_ptr<null_renderer>(new null_renderer());
+}
+
+bool null_renderer::renderer_register = gfx_renderer_factory::get_instance()->register_backend("null", null_renderer::create_func);