net: add peer network to CNodeStats

Summary:
This is a backport of core#20002 [1/5]
https://github.com/bitcoin/bitcoin/pull/20002/commits/6df7882029854f0427d84b22081018ae77e27e66

Test Plan: ninja

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10502