[backport#15638] [build] Move policy settings to new src/policy/settings unit
Summary:
This moves the following policy settings functions and globals to a new
src/policy/settings unit in lib_server:
- incrementalRelayFee
- dustRelayFee
- nBytesPerSigOp
- fIsBareMultisigStd
These settings are only required by the node and should not be accessed
by other libraries.
https://github.com/bitcoin/bitcoin/pull/15638/commits/4a75c9d6512a5580e60104103ea11d2cd9586354
Depends on D5963
This is a partial backport of Core PR15638
Test Plan:
ninja check check-functional
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Subscribers: deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D5967