[chronik-client] Add support for ws block extra data

Summary:
Add support for the avalanche invalidated ws block message type,
return the block timestamp and the coinbase data when applicable.

Test Plan:

npm run integration-tests

Reviewers: #bitcoin_abc, bytesofman

Reviewed By: #bitcoin_abc, bytesofman

Subscribers: bytesofman

Differential Revision: https://reviews.bitcoinabc.org/D16812