[FR] export users in JS/TS

**Is your feature request related to a problem? Please describe.**

I want to export my Firebase Authentication users in NodeJS [just as it's possible for Firestore](https://firebase.google.com/docs/firestore/solutions/schedule-export)

**Describe the solution you'd like**

```ts
import * as admin from "firebase-admin";
admin.auth().exportUsers({
outputUriPrefix: "gs://foo-bar",
});
```

**Describe alternatives you've considered**

[Using the CLI](https://firebase.google.com/docs/cli/auth)