htlcswitch: pass quit chans as unidirectional

This is a requirement for replacing the quit channel with a Context.
The Done() channel of a Context is always recv-only, so all users of
that channel must not expect a bidirectional channel.

htlcswitch/test_utils.go

@@ -1144,15 +1144,19 @@ func (h *hopNetwork) createChannelLink(server, peer *mockServer,
 		return nil
 	}
 
+	forwardPackets := func(linkQuit <-chan struct{}, _ bool,
+		packets ...*htlcPacket) error {
+
+		return server.htlcSwitch.ForwardPackets(linkQuit, packets...)
+	}
+
 	link := NewChannelLink(
 		ChannelLinkConfig{
-			BestHeight:    server.htlcSwitch.BestHeight,
-			FwrdingPolicy: h.globalPolicy,
-			Peer:          peer,
-			Circuits:      server.htlcSwitch.CircuitModifier(),
-			ForwardPackets: func(linkQuit chan struct{}, _ bool, packets ...*htlcPacket) error {
-				return server.htlcSwitch.ForwardPackets(linkQuit, packets...)
-			},
+			BestHeight:         server.htlcSwitch.BestHeight,
+			FwrdingPolicy:      h.globalPolicy,
+			Peer:               peer,
+			Circuits:           server.htlcSwitch.CircuitModifier(),
+			ForwardPackets:     forwardPackets,
 			DecodeHopIterators: decoder.DecodeHopIterators,
 			ExtractErrorEncrypter: func(*btcec.PublicKey) (
 				hop.ErrorEncrypter, lnwire.FailCode) {