Nodes: Access Remaining Compute Builtins

[cmhhelgeson]

Description

Adds the ability to access compute built-ins that are already defined by default directly within TSL. There are a few changes I made that I think might deserve further consideration.

1. Enabling subgroups by default if the feature is accessible: I largely did this to obviate the need for further logic within ComputeBuiltin that enables subgroups and activates the built-in should it be requested, or creating a separate node specifically for subgroup_size. However, we might not want to enable subgroups by default in every shader.

2. Creating ComputeBuiltinNode: A lot of the logic is similar to AttributeNode, however, I figured it would be better to separate accessing these builtins from accessing vertex attributes, as they serve different purposes, even if they are both considered 'attributes' within the context of the NodeBuilder.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	687.32 170.19	687.32 170.19	+0 B +0 B
WebGPU	835.97 224.07	837.63 224.53	+1.66 kB +454 B
WebGPU Nodes	835.48 223.95	837.14 224.41	+1.66 kB +457 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	463.24 111.86	463.24 111.86	+0 B +0 B
WebGPU	532.38 143.56	532.97 143.68	+585 B +123 B
WebGPU Nodes	489.04 133.42	489.63 133.53	+585 B +109 B