WebGPURenderer: Consistent bindFramebuffer() usage.

[Mugen87]

Related issue: #32503

Description

Similar to #32503 but for gl.bindFramebuffer().

Note: When we cache WebGL resources via WebGLState, we must use the interface everywhere otherwise the cached state does not match the real state which can lead to confusing bugs. So the native gl.bindFramebuffer() command should only be used in WebGLState.bindFramebuffer().

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	350.9 83.23	350.9 83.23	+0 B +0 B
WebGPU	616.16 171.02	616.22 171.03	+55 B +10 B
WebGPU Nodes	614.77 170.76	614.82 170.77	+55 B +13 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	483.14 118.07	483.14 118.07	+0 B +0 B
WebGPU	687.01 186.62	687.06 186.63	+55 B +11 B
WebGPU Nodes	636.85 173.83	636.9 173.84	+55 B +11 B