WebGLRenderer: Improve support of integer formats.

[Mugen87]

Fixed #28829.

Description

Improves the support for integer texture formats in WebGLRenderer. The WebGL backend of WebGPURenderer already has these checks.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	685.42 169.7	685.83 169.75	+405 B +54 B
WebGPU	828.45 222.25	828.45 222.25	+0 B +0 B
WebGPU Nodes	828.03 222.16	828.03 222.16	+0 B +0 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	462.02 111.48	462.42 111.53	+405 B +52 B
WebGPU	526.43 141.9	526.43 141.9	+0 B +0 B
WebGPU Nodes	483.08 131.72	483.08 131.72	+0 B +0 B