TSL: Introduces cache hierarchy

[sunag]

Related issue: Closes #28546

Description

The objective is that when using a node it will look in some parent if the variable has already been declared, similar to the block hierarchy adopted in JS for example.

[RenaudRohlinger]

Just tested as I had multiple times today the same issue as #28546 and this PR does seem to also introduce a small issue for the moment. 😁

Error comes from the CondNode I believe, when I call:

const hue2rgb = tslFn( ( [ p, q, t ] ) => {

	t = cond( t.lessThan( 0.0 ), t.add( 1.0 ), t );
	t = cond( t.greaterThan( 1.0 ), t.sub( 1.0 ), t );

	return cond(
		t.lessThan( 1.0 / 6.0 ),
		p.add( ( q.sub( p ) ).mul( 6.0 ).mul( t ) ),
		cond(
			t.lessThan( 1.0 / 2.0 ),
			q,
			cond(
				t.lessThan( 2.0 / 3.0 ),
				p.add( ( q.sub( p ) ).mul( float( 2.0 / 3.0 ).sub( t ) ).mul( 6.0 ) ),
				p
			)
		)
	);

} );

const palette = tslFn( ( [ t ] ) => {
    const color = hslToRgb(hue2rgb(...
    return color
})

particleMaterial.colorNode = palette( buffer.toAttribute().length() )

[sunag]

@RenaudRohlinger Since declaration of attributes, variables etc are related to cache we may have some revisions after this. I just update this PR, could you please let me know if it fixed it for you? Thanks for reporting the problem! :)

[RenaudRohlinger]

It does fix my issue! Thanks @sunag