[Apps][Examples] Create a websocket to listen for confirmation on a transaction

Summary:
T3203

Example using a chronik websocket to subscribe to a hash160 and txid. Upon receiving a Confirm ws event, the websocket unsubscribes and closes.

Test Plan: npm test

Reviewers: bytesofman, #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14359