Enable direct ad-hoc imports

`Can't find variable: IDBIndex` when setting up on Expo

I used the same hierarchy I had working on the web. I am not using performance or analytics, so I think all of the underlying components should work.

But, I believe that since there isn't a way (that I can tell) to import only specific components, I end up with an error as if I were importing performance package.

```
import React from 'react'
import { getAuth, connectAuthEmulator } from 'firebase/auth'
import { getFunctions, connectFunctionsEmulator } from "firebase/functions"
import { getStorage, connectStorageEmulator } from "firebase/storage"
import { getFirestore, connectFirestoreEmulator } from "firebase/firestore";
import { FirebaseAppProvider, useFirebaseApp, AuthProvider, StorageProvider, FirestoreProvider } from 'reactfire';

function FirebaseComponents({ children }) {
const app = useFirebaseApp() // a parent component contains a `FirebaseAppProvider`
const auth = getAuth(app)
const functions = getFunctions(app)
const firestoreInstance = getFirestore(app)
const storage = getStorage(app)

return (



{children}



);
}

function AllFirebaseComponents({ children, fire }) {
return (


{children}


)
}

export default AllFirebaseComponents
```

### Version info
"react": "^17.0.2",
"react-native": "~0.63.4",
"reactfire": "^4.2.0",
"firebase": "^9.0.1",

### Test case

TBU, will try to get one of these

### Steps to reproduce

Start a new expo app, attempt to use reactfire. Get error mentioned above.

### Expected behavior

Be able to import only the components needed, ex:
```
import FirebaseAppProvider from 'reactfire/FirebaseAppProvider';
```

### Actual behavior

I get the error mentioned above which I think comes from the performance stuff