WebGPURenderer: Fix early-z rejection

[sunag]

Related issue: #30862 (comment)

Description

This fix improve the ordering of opaque materials by optimizing early-Z rejection, rendering the opaque materials closest to the camera first. We certainly need a mechanism to improve GPU state switching overhead, it should be based on material type similarity rather than the order in which materials were created.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	336.49 78.38	336.49 78.38	+0 B +0 B
WebGPU	542.09 150.14	542.03 150.12	-58 B -16 B
WebGPU Nodes	541.55 150.03	541.5 150.02	-58 B -16 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	465.42 112.22	465.42 112.22	+0 B +0 B
WebGPU	614.93 166.19	614.87 166.17	-58 B -17 B
WebGPU Nodes	569.92 155.59	569.86 155.58	-58 B -15 B