automate sending ETH

[skaunov]

for permission-less kind of deals (MultiSig) it would be beneficial if Bisq could just propagate/send-out corresponding tx when the offer for buying via ETH is taken
maker would be saved from typing routine and mistyping risks, taker would enjoy fastest possible time, mediators would be off-loaded from this portion of trades since it hard to imagine a mediation case here

bisq-network/bisq2#1925