Make VectorFormatter support stateful formatters

Summary:
This is a backport of Core PR18112 [2/5]
https://github.com/bitcoin/bitcoin/pull/18112/commits/56dd9f04c701aa3ac340e95065bf83de20373c8b

Depends on D8786

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Differential Revision: https://reviews.bitcoinabc.org/D8787