multi: pass UpdateAddHtlc message custom records to invoice modifier

contractcourt/mock_registry_test.go

@@ -26,6 +26,7 @@ type mockRegistry struct {
 func (r *mockRegistry) NotifyExitHopHtlc(payHash lntypes.Hash,
 	paidAmount lnwire.MilliSatoshi, expiry uint32, currentHeight int32,
 	circuitKey models.CircuitKey, hodlChan chan<- interface{},
+	wireCustomRecords lnwire.CustomRecords,
 	payload invoices.Payload) (invoices.HtlcResolution, error) {
 
 	r.notifyChan <- notifyExitHopData{