net: pass CConnman via pointer rather than reference

Summary:
There are a few too many edge-cases here to make this a scripted diff.

The following commits will move a few functions into PeerLogicValidation, where
the local connman instance can be used. This change prepares for that usage.

This is a backport from commit 28f11e9406b185dc87144f1f29af0d93eb115b4e from Core.

Test Plan:

make check

Reviewers: #bitcoin_abc, schancel

Reviewed By: #bitcoin_abc, schancel

Subscribers: teamcity

Differential Revision: https://reviews.bitcoinabc.org/D1744