net: Add CNode::m_inbound_onion data member
Summary:
This is a backport of core#19998 [1/3]
https://github.com/bitcoin/bitcoin/pull/19998/commits/d4dde24034d7467883b290111da60527ab8048f8
Test Plan: ninja all check-all
Reviewers: #bitcoin_abc, majcosta
Reviewed By: #bitcoin_abc, majcosta
Differential Revision: https://reviews.bitcoinabc.org/D10456