Adapt webgpu samples Comput Boids demo

[Absulit]

Just adapt to POINTS

https://webgpu.github.io/webgpu-samples/?sample=computeBoids

[Absulit]

This got complicated because there's no ping pong buffers, which are later to be implemented in #272

some other ideas

storages.particlesA.copy(storages.particlesB);
points.copy(storages.particlesB, storages.particlesA);
storages.particlesA = storages.particlesB.value

will return to this later