swarm/network: Use actual remote peer ip in underlay (#19137)

* swarm/network: Logline to see handshake addr

* swarm/network: Replace remote ip in handshake uaddr

* swarm/network: Add test for enode uaddr rewrite method

* swarm/network: Remove redundance pointer return from sanitize

* swarm/network: Obeying the linting machine

* swarm/network: Add panic comment

(travis trigger take 1)