Once we have revealed our preimage to the world with a sweep attempt,
we can safely push our preimage to the server to speed up on chain
claim.
Rather than rely on the server, we use the state of our invoice in lnd
to determine whether we should continue trying to push the preimage to
the server.
We update to new set of server protos where new Terms calls are added.
Here static information will be returned from the server.
We no longer have a feebase+feerate, but get a final fee directly
returned by the server.
