config, net, test: asmap feature refinements and functional tests
Summary:
This PR builds on PR #16702 to add functional tests / sanity checks and user-facing refinements for passing -asmap to configure ASN-based IP bucketing in addrman. As per our review discussion in that PR, the idea here is to handle aspects like functional tests and config arg handling that can help the PR be merged while enabling the author to focus on the bucketing itself.
Backport of core PR17812.
Depends on D8198.
Test Plan:
ninja all check-all
Reviewers: #bitcoin_abc, jasonbcox
Reviewed By: #bitcoin_abc, jasonbcox
Differential Revision: https://reviews.bitcoinabc.org/D8200