Snapshot Support

[sambegin]

We should be able to constantly watch on data changes with specific queries. Firestore has what we call "snapshot" to open a listener on a collection or document. We should be able to do the same with Firesteer. Instead of doing a single and final GET request, we would open a snapshot and automatically refresh the main page content each time the snapshot is updated.

Snapshot reference : https://firebase.google.com/docs/firestore/query-data/listen