In this commit, we update all the taproot scripts spends to optionally
make the control block. This is useful in cases where we've already
created the control block, or may not have the items needed to construct
it in the first place.
We also add the control block to the sign descriptor itself.
In this commit, we update the `CommitSpendNoDelay` method to be aware of
the alternate spending mechanism for commitments that don't have a tweak
for the remote party's non-delay output. We also add a new witness type
so callers can convey their expected signing path.
This commit is a step to split the lnwallet package. It puts the Input
interface and implementations in a separate package along with all their
dependencies from lnwallet.
