Blender Git Loki

Cycles X: More flexible OIDN prefiltering settings

Allows to bring back old behavior when color and guiding passes are
denoised at the same time. Exposed as a single enum, so that we only
expose combinations which makes sense from configuration perspective.

Possibilities are:

- None. Assumes that the guiding passes are clean. Gives best results
without extra processing time (in expense of requiring to have enough
samples rendered to give clean guiding passes).

Corresponds to OIDN cleanAux=true and no prefiltering done on the
guiding passes.

- Fast. Old behavior, color and guiiding passes are denoised together.
This is fastest way of giving denoised result, in the expense of
possible loss of details.

Corresponds to OIDN cleanAux=false and no prefiltering.

- Accurate. Use special guiding passes prefilteringbefore denoising
color passes. Gives best results in the expense of extra time needed
to perform prefiltering. Avoids over-blurring details.

Corresponds to OIDN cleanAux=true and prefiltering performed on the
guiding passes.

Differential Revision: https://developer.blender.org/D12140