[Chronik] Add WsSubTokenId to WS subscribe to txs with a given token ID

Summary:
This allows users to subscribe to updates to a given token ID via WebSocket.

Depends on D15386.

Test Plan: ninja && ./test/functional/test_runner.py chronik_token_id_group

Reviewers: Fabien, #bitcoin_abc

Reviewed By: Fabien, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D15389