chainntnfs/tx_notifier: mark rescan as complete for transactions confirmed at tip
chainntnfs/tx_notifier: mark rescan as complete for transactions confirmed at tip

In this commit, we mark the rescan status for a transaction as complete
if we happen to detect it has confirmed within a new block that extends
the chain. We do this as otherwise, it's possible for us to not
immediately dispatch the notification upon a subsequent registration due
to the rescan state machine.

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