Plane: Add clampToLine to intersectLine().

[Mugen87]

Fixed #11474.

Description

As suggested in #11474 (comment), the PR adds a clampToLine parameter to Plane.intersectLine(). When true, the intersection is clamped to the line segment. The default is true so the change is fully backward compatible. By setting it to false, the use case of #11474 will work.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	361.4 85.82	361.4 85.82	+0 B +0 B
WebGPU	637.46 177.05	637.46 177.05	+0 B +0 B
WebGPU Nodes	635.58 176.76	635.58 176.76	+0 B +0 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	493.9 120.5	493.91 120.5	+14 B +9 B
WebGPU	709.2 191.87	709.22 191.87	+14 B +6 B
WebGPU Nodes	658.42 179.16	658.43 179.17	+14 B +6 B