Reduce MinConfs from 6 to 3 to allow faster swap attempts while the
server enforces risk-based confirmation requirements. Update
SelectDeposits to prioritize more-confirmed deposits first, increasing
the likelihood of server acceptance. Add client-side logging of
insufficient confirmation details from server error responses.
In this commit we add a new function SelectDeposits
to the loop-in manager. It coin-selects deposits that
meet an arbitrary swap amount provided by the client.
We have to ensure that the server creates the correct
change outputs for the htlc- and sweepless sweep
transactions.
