This may be useful for custom channel types that base everything off the index (a global value) rather than the output index (can change with each state).
This commit re-adds the LocalBalance and RemoteBalance fields to the
RevocationLog. The channeldb/migration30 is also adjusted so that anyone
who has not yet run the optional migration will not lose these fields if
they run the migration after this commit.
The reason for re-adding these fields is that they are needed if we want
to reconstruct all the info of the lnwallet.BreachRetribution without
having access to the breach spend transaction. In most cases we would
have access to the spend tx since we would see it on-chain at which time
we would want to reconstruct the retribution info. However, for the
watchtower subsystem, we sometimes want to construct the retribution
info withouth having access to the spend transaction.
A user can use the `--no-rev-log-amt-data` flag to opt-out of storing
these amount fields.
In this commit, a new `--db.no-rev-log-amt-data` flag is added. The
config option is passed though to everywhere that it will be used. Note
that it is still a no-op in this commit. An upcoming commit will make
use of the flag.
When testing serializing revocation log, we need to also copy its
`HTLCEntries` as the serialization of the HTLC involves a writing to the
`htlc.amtTlv` field.
This commit uses bigsize record to encode the htlc amount, which could
save us 3 more bytes if the encoded value is no greater than roughly
0.043 bitcoin. The uint test has been updated with a more realistic
values to reflect the actual gain.
