[net] Add addpeeraddress RPC method
Summary:
Allows addresses to be added to Address Manager for testing.
This is a backport of core#19658 [3/3]
https://github.com/bitcoin/bitcoin/pull/19658/commits/37a480e0cd94895b6051abef12d984ff74bdc4a3
Depends on D10070
Test Plan: ninja all check-all
Reviewers: #bitcoin_abc, majcosta
Reviewed By: #bitcoin_abc, majcosta
Differential Revision: https://reviews.bitcoinabc.org/D10071