DirectionalLight.gltf model is modeled inside out

Visualizing the world space geometry or shading normals on the face-culled geometry of the [DirectionalLight.gltf](https://github.com/KhronosGroup/glTF-Sample-Assets/tree/main/Models/DirectionalLight) shows that they are pointing to the inside
(here: color = N * 0.5f + 0.5f;)
Also visualizing the front-face condition showed that this is actually the front-face so vertex winding and normal on front-face is consistent.
Consequently, switching the three materials to double-sided shows the expected normal orientation of the outside of the spheres:

This results in black rendering with a ray tracer because the inside of the sphere is hit and light is blocked by the face-culled geometry in front. Switching to double-sided materials produces the correct result.

Start with the DirectionalLight.gltf asset linked in the issue and reproduce the problem using single-sided face culling and a ray tracer. Inspect the sphere geometry and its front-face behavior; done means the three materials render the sphere exteriors correctly without requiring double-sided materials.

Written by the indexing model from the issue text.