Make unstruct resolvable and introduce root.unwrap(TgpuVertexLayout)

[reczkok]

• Tests for unstruct resolution
• Tests for TgpuVertexLayout unwrapping
• Update docs
• Check if feasible to type check if every attribute has a location

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[reczkok]

• Check if feasible to type check if every attribute has a location

I experimented with this:

export type HasAllPropsWithLocations<T> = T extends TgpuVertexLayout<infer U>
  ? HasAllPropsWithLocations<U>
  : T extends WgslStruct | Unstruct
    ? {
        [K in keyof T['propTypes']]: HasAllPropsWithLocations<
          T['propTypes'][K]
        >;
      }[keyof T['propTypes']] extends false
      ? false
      : true
    : T extends { elementType: unknown }
      ? HasAllPropsWithLocations<T['elementType']>
      : HasCustomLocation<T> extends false
        ? false
        : true;

but keep running into Type instantiation is excessively deep and possibly infinite error

[mhawryluk]

what do we do about [~unstable] in published examples. I'd say we either

1. make vertexLayout stable, docs public and release 0.3.3 right after merging this PR
2. make boids experimental
3. do nothing

[reczkok]

I'm kinda a fan of option 1

[iwoplaza]

A suggestion, this wording might suggest more that:

• It's something the dev has to do manually,
• This usually happens automatically, but it's a requirement when trying to unwrap

Suggested change

	To unwrap a `TgpuVertexLayout` make sure that all its attributes are marked with the appropriate location.
	To unwrap a `TgpuVertexLayout` make sure to explicitly mark each of its attributes with the appropriate location using `d.location(...)`.

[iwoplaza]

Let's stick to PascalCase for structs.

Suggested change

	const vertexInfo = d.unstruct({
	const VertexInfo = d.unstruct({