feat: Second argument to `.as` for reinterpretation

This is equivalent in function to creating a new typed buffer and plugging in an existing GPUBuffer, but we can validate that the size of the schemas matches. Also, it's pretty cool.

const size = 4;

const array2d = <T extends AnyWgslData>(element: T, w: number, h: number) =>
  d.arrayOf(d.arrayOf(d.vec2h, w), h);

const displacementBuffer = root.createBuffer(array2d(d.vec2h, size, size)).$usage('storage');

const regularView = noiseBuffer.as('mutable');
const packedView = noiseBuffer.as('mutable', array2d(d.u32, size, size));

We could also go for a .reinterpret API, which would nicely extend to fixed usages:

const size = 4;

const array2d = <T extends AnyWgslData>(element: T, w: number, h: number) =>
  d.arrayOf(d.arrayOf(d.vec2h, w), h);

const displacementMutable = root.createMutable(array2d(d.vec2h, size, size));
const displacementPackedMutable = displacementMutable.reinterpret(array2d(d.u32, size, size));

To be discussed before attempting to implement

No files or tests are named. Start by reviewing the existing .as and createBuffer entry points, then compare the proposed second argument with the alternative .reinterpret API; first resolve the API choice and schema-size validation behavior before attempting implementation.