[Chronik] Add plugin group tx history

Summary:
Add tx history of groups assigned by plugins using GroupHistory{Writer,Reader} and MempoolGroupHistory, and add the corresponding HTTP endpoints /plugin/:plugin_name/:group_hex/{confirmed-txs,unconfirmed-txs,history}.

Depends on D16723.

Test Plan: ./test/functional/test_runner.py chronik_plugins

Reviewers: Fabien, #bitcoin_abc

Reviewed By: Fabien, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D16708