Add `createParticles` and `particles`

[quinton-ashley]

Add GPU accelerated particle system support to q5 WebGPU, similar to ParticleContainer in Pixi.js.

Example usage:

await Canvas();

let starImg = loadImage('star.png');

let stars = createParticles(100, starImg);

for (let star of stars) {
  star.x = jit(10);
  star.y = jit(10);
  star.vx = jit(1);
  star.vy = jit(1);
  star.tint = color(random(), 1, 1);
}

q5.draw = () => {
  particles(stars);
};

Canvas2D mode would have a polyfill for it.