Review and hopefully simplify link() API

[mighdoll]

Current API:

// load wgsl text (using vite syntax. see Build Support below.)
const wgsl = import.meta.glob("./shaders/*.wgsl", {
  query: "?raw",
  eager: true,
  import: "default",
});

// register the linkable exports
const registry = new ModuleRegistry({ wgsl });

// link my main shader wgsl with imported modules,
// using the provided variables for import parameters 
const code = registry.link("main", { WorkgroupSize: 128 });

// pass the linked wgsl to WebGPU as normal
device.createShaderModule({ code });