Optimize solari initial and temporal DI

[SparkyPotato]

Objective

Optimizes the initial + temporal ReSTIR DI pass. In the example cornell box scene, it goes from 2.37 ms to 1.97 ms. On a more complex scene, the Lumberyard bistro, with many emissive lights, it goes from 130+ ms to about 80.8 ms at 1440p on a 4070.

I also noticed that triangle area calculation didn't take object scale into account and fixed that.

Solution

• Switch to textures instead of buffers for reservoir storage.
• There's also a bunch of other micro-optimizations to increase SM occupancy and reduce memory pressure.

Testing

• This was tested on the cornell box example scene and bistro.
• Everything was tested on Windows 11 with a 4070 running at 1440p. Testing on other platforms and GPUs by running the example.

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Showcase

[alice-i-cecile]

Please add this PR (and yourself!) to the draft release notes :)