ViewportDepthNode: Support reversed depth in viewZ functions.

[Mugen87]

Related issue: #32967

Description

FX effects relying on converting depth values to viewZ values (like DoF) should now work with reversed depth buffer.

It seems getViewPosition() is already compatible with reversed depth buffer since it works with the inverse projection matrix (which values depend on the type of depth buffer).

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	359.14 85.24	359.14 85.24	+0 B +0 B
WebGPU	623 173.3	623.22 173.39	+219 B +91 B
WebGPU Nodes	621.58 173.05	621.8 173.14	+219 B +89 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	490.87 119.65	490.87 119.65	+0 B +0 B
WebGPU	696.71 188.35	696.79 188.39	+81 B +35 B
WebGPU Nodes	645.91 175.75	645.99 175.78	+81 B +36 B