[chronik] Add an avalanche invalidated block ws message
Summary:
This message triggers upon block invalidated by avalanche.
Depends on D16802.
Test Plan:
ninja all check-all
Reviewers: #bitcoin_abc, PiRK, tobias_ruck
Reviewed By: #bitcoin_abc, PiRK, tobias_ruck
Subscribers: tobias_ruck, PiRK, bytesofman
Differential Revision: https://reviews.bitcoinabc.org/D16803