Added option WithSkippedTxns, which has one historical problematic tx by default.
Sweeps originating from these transactions are omitted when reading from DB.
loopdb: add column sweep_batches.cancelled and replaced DropBatch with
CancelBatch. It is needed, because sweep.batch_id is a foreign key to batch.
Changed StoreMock.InsertSweepBatch not to reuse batch_id. This is needed by
the test, which checks that new batch has fresh ID.
SwapHash used to be a key in the sweeps table. Now the key is outpoint which
replaces columns outpoint_txid and outpoint_index. In-memory structures and unit
tests were also updated to use outpoint as key. Outpoint is truly unique.
Previously, when handling a sweep we assumed that if a sweep status
was completed, the parent batch was also finished. However, since the
batch confirmation status depends on three on-chain confirmations, it
is possible that a spend notifier was started for a sweep of an active
batch. The notifier would fetch the parent batch from the database, but
because we incorrectly assumed that the parent was confirmed (when it
was not), the DB call would fail with a 'no rows returned' error.
This failure would cause the sweep to fail and the sweep batcher to
stop, resulting in a permanent failure state.
This data is not used by Batcher since commit
"sweepbatcher: load swap from loopdb, not own store".
Now sweepbatcher.Store depends only on tables sweeps and sweep_batches
and does not depend on swaps, loopout_swaps and htlc_keys, making it
easier to reuse.
