WebGPURenderer: Improve cache key verification

[sunag]

Related issue: #32134

Description

This makes LightsNode, even though the file is unchanged in this PR, the same cache key for other passes, reusing the same TSL code generated when using different scenes, especially if .render(mesh, camera) is used.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	354.98 86.28	354.98 86.28	+0 B +0 B
WebGPU	606.17 169.96	606.33 170	+162 B +34 B
WebGPU Nodes	604.78 169.7	604.94 169.73	+162 B +31 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	486.63 121.03	486.63 121.03	+0 B +0 B
WebGPU	675.27 185.34	675.44 185.38	+162 B +42 B
WebGPU Nodes	617.27 168.57	617.43 168.61	+162 B +35 B