WebGPURenderer: Add Array Type Variable Declaration Support

[RenaudRohlinger]

Fixed: #30097

Description

This PR introduces the support of array type in variable declarations in both WGSL and GLSL backends.

Example usage:

const a = vec2().toVar( 'a' ).toArray( 10 );

// assign first element of the array of vec2
a.element(0).assign(vec2(10, 10))

// access to the first element of the array of vec2
const b = a.element(0).add(1);

Related comment: #30097 (comment)

This PR cover array of var so far.
Next we could also support array of Const with a new syntax such as Const([vec2(),vec2()]) by updating NodeVar to take an optional array as node argument and by updating the generateConst of the NodeBuilder to support assigning array types:

generateConst(type, value = null, length = undefined) {
    // Handle array types
    if (length && length > 1) {
        if (value === null || !Array.isArray(value)) {
            // Create default array with the base type's default value
            const defaultValue = this.generateConst(type);
            return `array<${this.getType(type)}, ${length}>(${Array(length).fill(defaultValue).join(', ')})`;
        }

        // Generate array with provided values
        const arrayValues = value.map(v => this.generateConst(type, v)).join(', ');
        return `array<${this.getType(type)}, ${length}>(${arrayValues})`;
    }
    ....

This contribution is funded by Utsubo

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	336.25 78.28	336.25 78.28	+0 B +0 B
WebGPU	510.39 141.66	510.82 141.8	+434 B +136 B
WebGPU Nodes	509.86 141.55	510.29 141.69	+434 B +136 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	465.25 112.13	465.25 112.13	+0 B +0 B
WebGPU	584.39 158.38	584.82 158.5	+434 B +126 B
WebGPU Nodes	539.77 147.93	540.21 148.06	+434 B +131 B

[sunag]

I had created an implementation for this, I was going to publish it today ^^

[sunag]

Sorry for not letting you know in advance, I also didn't think you'd be working on this :/
#30386

The implementation I made already matches .toConst() and .toVar() and does the auto-caching if neither of them are used.
You can enter an array as a parameter, this allows users to create array constants with predefined parameters.

The idea of ​​having an array as parameters can help us create multi-dimensional arrays (soon).

[sunag]

I know this is irrelevant now, but perhaps my mistake was not publishing the draft earlier.

[RenaudRohlinger]

closed in favor of #30386