[Cashtab] [Chronik Websocket Notifications] [Part 2] Get Hash160s from wallet

Summary:
T2447

Depends on D11530

Helper function getHashArrayFromWallet(wallet) and unit tests. Gets hash160s from active wallet. These are required for chronik websocket, which subscribes to hash160 and not addresses.

If wallet does not have hash160s (unmigrated), function returns false. In this edge case (as with websocket failures), the app will use alternate notifications.

Test Plan: npm test

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Subscribers: emack

Differential Revision: https://reviews.bitcoinabc.org/D11531