[chronik] Add more data to the blocks ws message

Summary:
This especially makes disconnected blocks debugging easier, where this data cannot be retrieved after the ws message like it is upon connection or finalization because the block is parked and Chronik only indexes the active chain.

Because timestamp can be used for every message at low cost, it's included unconditionally.

Depends on D16803.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, tobias_ruck

Reviewed By: #bitcoin_abc, tobias_ruck

Subscribers: tobias_ruck

Differential Revision: https://reviews.bitcoinabc.org/D16805