[chronik-client] Support websockets in ChronikClientNode

Summary: Support for websocket connections to in-node versions of chronik

Test Plan:
See D14915 for instructions or wait for CI

npm test for new subscription validation function

Reviewers: #bitcoin_abc, Fabien, tobias_ruck

Reviewed By: #bitcoin_abc, Fabien, tobias_ruck

Subscribers: tobias_ruck, PiRK, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D15412