swap: refactor htlc construction to allow passing of internal keys

This commit is a refactor of how we construct htlcs to make it possible
to pass in internal keys for the sender and receiver when creating P2TR
htlcs. Furthermore the commit also cleans up constructors to not pass in
script versions and output types to make the code more readable.

loopin.go

@@ -404,26 +404,26 @@ func validateLoopInContract(lnd *lndclient.LndServices,
 // initHtlcs creates and updates the native and nested segwit htlcs
 // of the loopInSwap.
 func (s *loopInSwap) initHtlcs() error {
-	if IsTaprootSwap(&s.SwapContract) {
-		htlcP2TR, err := s.swapKit.getHtlc(swap.HtlcP2TR)
-		if err != nil {
-			return err
-		}
-
-		s.swapKit.log.Infof("Htlc address (P2TR): %v", htlcP2TR.Address)
-		s.htlcP2TR = htlcP2TR
-
-		return nil
-	}
-
-	htlcP2WSH, err := s.swapKit.getHtlc(swap.HtlcP2WSH)
+	htlc, err := GetHtlc(
+		s.hash, &s.SwapContract, s.swapKit.lnd.ChainParams,
+	)
 	if err != nil {
 		return err
 	}
 
-	// Log htlc addresses for debugging.
-	s.swapKit.log.Infof("Htlc address (P2WSH): %v", htlcP2WSH.Address)
-	s.htlcP2WSH = htlcP2WSH
+	switch htlc.OutputType {
+	case swap.HtlcP2WSH:
+		s.htlcP2WSH = htlc
+
+	case swap.HtlcP2TR:
+		s.htlcP2TR = htlc
+
+	default:
+		return fmt.Errorf("invalid output type")
+	}
+
+	s.swapKit.log.Infof("Htlc address (%s): %v", htlc.OutputType,
+		htlc.Address)
 
 	return nil
 }