Solari v8: Disable ReSTIR by default

[JMS55]

Objective

• Denoisers are already spatial and temporal reuse. Do we need ReSTIR? Testing shows, not really!
• For direct lighting, plain RIS is already pretty good (and I plan on adding ReGIR), and for indirect lighting, the world cache helps (and we could use it to further guide screen-space paths). It's better to use cheap methods to reduce noise, and then lean on the denoiser for the rest from what I've found.

Solution

• Add a ReSTIR toggle to SolariLighting (ReSTIR is now off by default)
• Without ReSTIR, performance is ~twice as fast on my RTX 3080. There's also significant memory savings (need less buffers, and no temporal TLAS!) , a significant reduction in code complexity (ReSTIR adds so much math that's very easy to get wrong), and avoids issues like correlations and boiling that confuses the denoiser.
• The only downside is that quality is regressed a little bit, notably in small shadow detail, and in tricky lighting conditions. For most people, I think the vast performance increase is very much worth it.

AI was used to perform the vast majority of the mechanical work here, as it's mostly boring plumbing.

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Showcase

ReSTIR Enabled
https://cdn.discordapp.com/attachments/1385299007445930135/1540790234495713350/image.png?ex=6a8b3c3a&is=6a89eaba&hm=a700233fd6b6b0570ba8c7555605221fd37ac3ea3959d5b1ca6a35d677298dcd&
https://cdn.discordapp.com/attachments/1385299007445930135/1540790314636410941/image.png?ex=6a8b3c4d&is=6a89eacd&hm=d0a9fac32c024c1c6a88355961851ef4e64ca3f354de8a9191daedd6c1a646e3&

ReSTIR Disabled
https://cdn.discordapp.com/attachments/1385299007445930135/1540790233594069103/image.png?ex=6a8b3c3a&is=6a89eaba&hm=9ad094f65e4e6966d65d3c723defe94434a342d3960b66b7bf3841ef26533e14&
https://cdn.discordapp.com/attachments/1385299007445930135/1540790315638587464/image.png?ex=6a8b3c4d&is=6a89eacd&hm=afd72bc11ea8417e10db34ba2ae3f2dc39147157274f8a13c14f41cb687d3e02&

[stuartparmenter]

setup_raytracing_scene_needs_previous_frame_data can remove this every frame, might be worth updating the docs

[stuartparmenter]

Anyone actually using these in their app would break if these get removed here wouldn't they?