Add CustomUintFormatter

Summary:
This is a backport of Core PR18112 [4/5]
https://github.com/bitcoin/bitcoin/pull/18112/commits/e574fff53eec4a27c83b765cb69e31d8399047ea

Depends on D8788

Test Plan: ninja

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Subscribers: majcosta

Differential Revision: https://reviews.bitcoinabc.org/D8789