[net] Return CService from GetLocalAddrForPeer and GetLocalAddress

Summary:
This is a partial backport of core#25514
https://github.com/bitcoin/bitcoin/pull/25514/commits/5961f8eea1ad5be1a4bf8da63651e197a20359b2

Depends on D14748

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14749