channeldb: implement serialization of onion addresses
channeldb: implement serialization of onion addresses

Co-Authored-By: Eugene <75ca2b81262d080125e72169f41e438fea01f0d9@users.noreply.github.com>

aakselrod/lnd,aakselrod/lnd,LightningNetwork/lnd,LightningNetwork/lnd