TSL: add mat convert

[z4122]

Support mat4 to mat3 and mat3 to mat2 in TSL.
In glsl, mat3(mat4) is a convinent method to convert matrix, it will help simpify code.

before

const bm = mat3(
			batchingMatrix[ 0 ].xyz,
			batchingMatrix[ 1 ].xyz,
			batchingMatrix[ 2 ].xyz
		 );

after

const bm = mat3( batchingMatrix );

Because WGSL doesn't support code like mat3(mat4). So it will be split into different part in NodeBuilder.js

if ( fromTypeLength === 16 && toTypeLength === 9 ) {

      return `${ this.getType( toType ) }(${ snippet }[0].xyz, ${ snippet }[1].xyz, ${ snippet }[2].xyz)`;

    }

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize dev	Filesize PR	Diff
683.5 kB (169.2 kB)	683.5 kB (169.2 kB)	+0 B

🌳 Bundle size after tree-shaking

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

Filesize dev	Filesize PR	Diff
460.7 kB (111.1 kB)	460.7 kB (111.1 kB)	+0 B