internal Utility function to render the given Scene to a render target and capture one of the render buffers, defined by VisualizationMode. Not clear where the valid VisualizationMode FNames are defined, possibly this list: "BaseColor,Specular,SubsurfaceColor,WorldNormal,SeparateTranslucencyRGB,,,WorldTangent,SeparateTranslucencyA,,,Opacity,SceneDepth,Roughness,Metallic,ShadingModel,,SceneDepthWorldUnits,SceneColor,PreTonemapHDRColor,PostTonemapHDRColor"