input+lnwallet: Add scripts for CSV delayed HTLC outputs

We also increase the witness size for these types to account for the 3
extra bytes. The size won't be correct in all cases, but it is just an
upper bound in any case.

sweep/txgenerator_test.go

@@ -14,7 +14,7 @@ var (
 		input.HtlcOfferedRemoteTimeout,
 		input.WitnessKeyHash,
 	}
-	expectedWeight  = int64(1459)
+	expectedWeight  = int64(1462)
 	expectedSummary = "1 CommitmentTimeLock, 1 " +
 		"HtlcAcceptedSuccessSecondLevel, 1 HtlcOfferedRemoteTimeout, " +
 		"1 WitnessKeyHash"