routing: add source parameter to query routes

This commit allows execution of QueryRoutes from any source node.
Previously this was restricted to only the self node.

routing/pathfind_test.go

@@ -1712,7 +1712,7 @@ func TestPathFindSpecExample(t *testing.T) {
 	carol := ctx.aliases["C"]
 	const amt lnwire.MilliSatoshi = 4999999
 	routes, err := ctx.router.FindRoutes(
-		carol, amt, noRestrictions, 100,
+		bobNode.PubKeyBytes, carol, amt, noRestrictions, 100,
 	)
 	if err != nil {
 		t.Fatalf("unable to find route: %v", err)
@@ -1779,7 +1779,7 @@ func TestPathFindSpecExample(t *testing.T) {
 	// We'll now request a route from A -> B -> C.
 	ctx.router.routeCache = make(map[routeTuple][]*Route)
 	routes, err = ctx.router.FindRoutes(
-		carol, amt, noRestrictions, 100,
+		source.PubKeyBytes, carol, amt, noRestrictions, 100,
 	)
 	if err != nil {
 		t.Fatalf("unable to find routes: %v", err)