get config via chainstatemanager when possible (4/n)
Summary:
Access the config via the chainman option for ProcessNewBlock, ProcessNewBlockHeader, AcceptBlockHeader
Depends on D15802
Test Plan: ninja all check-all
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D15807