Add a new render setting to turn on the OptiX denoiser for beauty

[sirpalee]

There should be a render setting to turn on the Optix denoiser for the beauty AOV.

The difficulty here is that the composition, responsible for differentiating between background and foreground pixels, happens at the moment per bucket, and the Optix denoised beauty is available at a different rate than the non-denoised ID and P AOV. We need to remove the requirement of having all 3 buffers available at the same time for each bucket and update how composition behaves.

[sirpalee]

Depends on #8

[autodesk-oss-arnold-bot[bot]]

Issue synced internally to ARNOLD-13213

[compso]

invalid