Instead of hard erroring, we now surface module not found errors as
TypeScript diagnostics (we have yet to show the source code of the
error, but something we can improve over time).
Support for Wasm modules.
Note this implements the standard where the default export is the
instance (not the module). The module will come later with source phase
imports.
```ts
import { add } from "./math.wasm";
console.log(add(1, 2));
```
