TSL: Introduce tangentViewFrame and bitangentViewFrame

[sunag]

Related issue: #31059 (comment), #30837 (comment), #31271

Description

Introduce tangentViewFrame, bitangentViewFrame and fixed the incompatibilities between using material.flatShading=true or geometry.computeTangents().

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	337.54 78.73	337.54 78.73	+0 B +0 B
WebGPU	556.43 154.15	556.74 154.17	+318 B +26 B
WebGPU Nodes	555.78 153.99	556.1 154.01	+318 B +25 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	468.74 113.38	468.74 113.38	+0 B +0 B
WebGPU	632.24 171.08	632.55 171.18	+317 B +102 B
WebGPU Nodes	587.24 160.39	587.56 160.5	+317 B +111 B