Allow instantiateOnFaces block of node geometry to infer UV coordinates

[PatrickRyanMS]

Right now the instantiateOnFaces block does not provide UV coordinates for the position generated on the face. Could the block infer UV coordinates so that it could be used in conjunction with TextureFetch? That could be too slow, and if so, maybe we need to kick a warning in the build log that the block does not provide UV coordinates so users can see to use instantiateOnVertcies instead.

Below is a graph to test with containing a Texture to determine if a cube or null is passed based on the instantiate position.
instantiateOnFacesTest.zip