bug: unnecessary conversion to common type for `<<` and `>>` operators

This code
```ts
const repro = () => {
  'use gpu';
  const x = d.i32(8);
  return x << d.u32(2);
};

console.log(tgpu.resolve([repro]));
```
resolves to
```rust
fn repro() -> i32 {
  const x = 8i;
  return (x << 2i);
}
```
which is invalid wgsl :((