multi: remove LightningNode from ChannelEdgePolicy

Finally, The LightningNode object is removed from ChannelEdgePolicy.
This is a step towards letting ChannelEdgePolicy reflect exactly the
schema that is on disk.

This is also nice because the `Node` object is not necessarily always
required when the ChannelEdgePolicy is loaded from the DB, so now it
only get's loaded when needed.

routing/router_test.go

@@ -1431,9 +1431,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 		MinHTLC:                   1,
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
-		Node: &channeldb.LightningNode{
-			PubKeyBytes: edge.NodeKey2Bytes,
-		},
+		ToNode:                    edge.NodeKey2Bytes,
 	}
 	edgePolicy.ChannelFlags = 0
 
@@ -1450,9 +1448,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 		MinHTLC:                   1,
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
-		Node: &channeldb.LightningNode{
-			PubKeyBytes: edge.NodeKey1Bytes,
-		},
+		ToNode:                    edge.NodeKey1Bytes,
 	}
 	edgePolicy.ChannelFlags = 1
 
@@ -1528,9 +1524,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 		MinHTLC:                   1,
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
-		Node: &channeldb.LightningNode{
-			PubKeyBytes: edge.NodeKey2Bytes,
-		},
+		ToNode:                    edge.NodeKey2Bytes,
 	}
 	edgePolicy.ChannelFlags = 0
 
@@ -1546,9 +1540,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 		MinHTLC:                   1,
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
-		Node: &channeldb.LightningNode{
-			PubKeyBytes: edge.NodeKey1Bytes,
-		},
+		ToNode:                    edge.NodeKey1Bytes,
 	}
 	edgePolicy.ChannelFlags = 1