Support passing custom `AbortSignal` (would need to disable socketTimeout if signal passed)

## Use case

```js
const controller = new AbortController();
setTimeout(0, () => controller.abort());

const result = await fetch("https://google.com", { signal: controller.signal });
```

Start by locating the fetch wrapper and its existing socketTimeout handling, then inspect how request options are passed through to node-fetch. Confirm the expected behavior for a caller-supplied AbortSignal and verify it with the project's existing test or request flow; done means the provided signal can abort the fetch without the conflicting socket timeout.

Written by the indexing model from the issue text.