InstanceNode: Add support for StorageInstancedBufferAttribute

[RenaudRohlinger]

Description
Add support for direct usage of StorageInstancedBufferAttribute for instanceMatrix of InstancedMesh (or any type of Mesh tagged with mesh.isInstancedMesh.

For example:

const instanceMatrixStorage = new THREE.StorageInstancedBufferAttribute()

const instancedMesh = new THREE.InstancedMesh(geometry, material, count)
instancedMesh.instanceMatrix = instanceMatrixStorage

// -> No need for any tricky patch in positionNode or vertexNode anymore nor buffer duplication and update in InstancedNode

Can be very useful for advanced usage without having to create complex nodes by naturally make use of the InstancedNode and NodeMaterial pipeline.

Alternative would be to expose InstanceNode and patch via prototype the old WebGLRenderer way which I don't recommend.

This contribution is funded by Utsubo & Three.js Blocks

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	356.24 86.48	356.24 86.48	+0 B +0 B
WebGPU	615.49 172.75	615.97 172.86	+476 B +110 B
WebGPU Nodes	614.1 172.5	614.57 172.61	+476 B +109 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	488.04 121.25	488.04 121.25	+0 B +0 B
WebGPU	684.96 188.02	688.25 188.83	+3.29 kB +803 B
WebGPU Nodes	626.68 171.22	629.97 172.05	+3.29 kB +827 B

[Mugen87]

Unrelated side note: This comment isn't 100% correct since the WebGL 2 backend has a guaranteed size of only 16KB, see #30560 (comment). 64KB is supported on most platforms though. It would still be safer to set count to a smaller value.