Feature: Add Firestore unwrap data hooks

[davideast]

Description

Add hooks that unwrap the QuerySnapshot returned from a reference.

Code sample

interace Person {
  id: string;
  name: string;
}

function ProfileComponent() {
  const peopleRef = firestore.collection('people');
  const personRef = peopleRef.doc('david');

  const person = useFirestoreDocData<Person>(personRef, { idField: 'id' });
  const people = useFirestoreCollectionData<Person>(ref, { idField: 'id' });
  
  return (
    <h1>{person.name}</h1>
    <ul>
       {people.map(p => <li>{p.name}</li>}
    </ul>
  );
}