input/size: split constants into confirmed/non-confirmed

This to more easily track mismatches if constants and get more accurate
fee estimates for the two channel types.

The non-anchor weight estimates will now be smaller, this is okay since
these constants are only being used for fee estimation (and will now be
more accurate).

sweep/txgenerator_test.go

@@ -15,7 +15,7 @@ var (
 		input.HtlcOfferedRemoteTimeout,
 		input.WitnessKeyHash,
 	}
-	expectedWeight  = int64(1463)
+	expectedWeight  = int64(1460)
 	expectedSummary = "0000000000000000000000000000000000000000000000000000000000000000:10 (CommitmentTimeLock), " +
 		"0000000000000000000000000000000000000000000000000000000000000001:11 (HtlcAcceptedSuccessSecondLevel), " +
 		"0000000000000000000000000000000000000000000000000000000000000002:12 (HtlcOfferedRemoteTimeout), " +