get config via chainstatemanager when possible (5/5)

Summary:
Access the config via the chainman's m_options member in LoadExternalBlockFile, VerifyDB, AcceptBlock

After this commit, the only validation functions that still need to be passed a config argument are in ATMPArgs and BlockValidationOptions

Depends on D15807

Test Plan:
With chronik
ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D15808