CYCLES_TEST_DEVICES is a list of devices (CPU, CUDA, OPTIX, OPENCL). It is set
to CPU only by default.
Test output is now writen to build/tests/cycles/<device>, and the HTML report
has separate report pages for the different devices, with option to compare
between CPU and GPU renders.
Various GPU tests are still failing due to CPU/GPU differences, these are to be
fixed or blacklisted still.
Ref T82193
