This commit adds tests for the outputs of the light path node.
This include many typical tests (E.g. Changing the colour of a material
based on if it's a camera ray or not) along with some "unusual" tests.
Examples include:
- Testing many of the light path node outputs on lights.
- This includes "analytical" lights and mesh lights, which can behave
differently depending on if Next Event Estimation or forward path
tracing occurs.
- Adding extra objects using ray portal BSDFs and transparent BSDFs
just to double check they don't introduce their own issues.
Ref: blender/blender-test-data!55
01d80cee28