Add WebGPU files

[joshuaellis]

Describe the feature you'd like:

One of the biggest pieces of three that unknowingly to me is missing, is the webgpu and nodes files missing from examples/jsm/renderers. I've had a go myself at piecing it together and I think it needs someone who really understands it to make it work properly without countless bugs.

I do know currently you need to add @webgpu/types to the project as gpu is not yet officially extended from Navigator. There's a branch already with some work if someone wants to pick it up – r126-node-materiallight, but anyone is welcome to start from scratch.

Of course, we're all here to support where we can, this isn't a lone effort and it'd be great to have this in the repo.

[CodyJasonBennett]

Following #240, should I give this a go?

[joshuaellis]

If you're interested, yes that would be great. Afaik we're still missing this.