net: Add alternative port for onion service
Summary:
This change allows to distinguish incoming Tor connections from others.
This is a backport of core#19991 [2/8]
https://github.com/bitcoin/bitcoin/pull/19991/commits/a5266d4546c444cfd6d36cb63d2df52ce9e689e2
Depends on D10444
Test Plan: ninja all check-all
Reviewers: #bitcoin_abc, majcosta
Reviewed By: #bitcoin_abc, majcosta
Differential Revision: https://reviews.bitcoinabc.org/D10445