[Chronik] Add address subscription functionality to websocket.rs in bitcoinsuite-chronik-client

Summary:
Uses subscribe_to_address() and unsubscribe_from_address() methods with CashAddress objects to subscribe / unsubscribe events

Internally converts addresses to their underlying script hashes (P2PKH/P2SH) for subscription

Test Plan:
Please set BUILD_DIR env to export BUILD_DIR="/path/to/build_dir
UNIX: ./contrib/teamcity/build-configurations.py build-bitcoinsuite-chronik-client

Reviewers: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Reviewed By: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D18168