Math: Add convenience methods

[WestLangley]

In ColorManagement.js this pattern is used:

three.js/src/math/ColorManagement.js

Lines 48 to 50 in 820b3bf

	_vector.set( color.r, color.g, color.b ).applyMatrix3( LINEAR_DISPLAY_P3_TO_LINEAR_SRGB );
	return color.setRGB( _vector.x, _vector.y, _vector.z );

This PR adds convenience methods to simplify these calculations:

Vector3.setFromColor( c )
Color.setFromVector3( v )
Color.applyMatrix3( m )

/ping @donmccurdy

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize	Gzipped	Diff from dev
618 kB	154.7 kB	+282 B

🌳 Bundle size after tree-shaking

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

Filesize	Gzipped	Diff from dev
409.7 kB	100.8 kB	+282 B

[WestLangley]

I inlined this method to avoid an unnecessary conversion to -- and from -- a Vector3.

[donmccurdy]

Thanks @WestLangley! Being able to apply a Matrix3 directly to a Color is helpful for sure. Now that we can do that, perhaps we don't need the to/from Vector3 methods? Or do you think there are other cases requiring that conversion? Either way is OK with me.

[WestLangley]

@donmccurdy I added those methods because Vector3 already supports conversion from multiple classes.

I was thinking we will have to support proper gamut mapping. It remains to be seen how that will be implemented.

[donmccurdy]

Ok — I'm unsure about whether we will need to provide gamut mapping methods, but have no concerns with keeping these methods.