final material info node

It would be handy when creating custom AOV's to be able to get information about the finalised material. A 'final material info' node could be connected to the AOV output node so that information about the material could be used in compositing.

Example sockets that it would be useful for the node to have could include:

1. roughness
2. . specular
3. . subsurface
4. . metallic
5. . IOR
6. . Emission strength
7. . volume density
8. . volume temperature

It's difficult to gather the final values of such data because the material could comprise multiple shaders all of which manipulate the values separately. Combine that with different shaders being potentially combined with masks, it becomes extremely difficult to calculate.