lnwallet/channel: init localUpdateLog with index from remoteCommit, remoteUpdateLog from localCommit
lnwallet/channel: init localUpdateLog with index from remoteCommit,
remoteUpdateLog from localCommit

This commit fixes a bug within channel.go that would lead to the
content of the update logs and their indexes getting out of sync during
restores.

The scenario that could occur was that the localUpdateLog was initiated
with a log index taken from the localCommitment. Updates we send (which
are added to the localUpdateLog) will be added to the remote commitment
first. The problem happened when an update was sent and added to the
remote commitment, but not ACKed. Since it was not ACKed, we would not
add it to our local commitment. During a restart/restore we would init
the localUpdateLog with a height too low, such that when going through
the outgoing HTLCs on the remote commitment, we would restore an HTLC at
an index higher than our local log HTLC counter.

The symmetric change is done to the remoteUpdateLog.

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