https://github.com/TwoTailsGames/Unity-Built-in-Shaders/blob/master/DefaultResourcesExtra/Internal-BlitCopy.shader
https://forum.unity.com/threads/how-to-use-hidden-blitcopy-shader.447041/
https://forum.unity.com/threads/commandbuffer-blit-with-no-custom-shader-commandbuffer-blit-with-internal_blitcopy-shader.432699/?_ga=2.14217399.1451532328.1581996272-2034114505.1564371644
