Import named `Disposable` is not moved when moving code to another file

```ts
// @filename: src/_producer.ts
export class Disposable {}
```

```ts
// @filename: src/_consumer.ts
import { Disposable } from './_producer';

class Something extends Disposable {
}
```
Doing move to a new file on `Something` generates the following 🐛 (note how `Disposable` is not imported from `_producer.ts`):

```ts
// @filename: src/Something.ts
class Something extends Disposable {
}

```