itest: add route blinding dummy hops test

Add an itest that tests the addition of dummy hops to a blinded path. By
testing that invoices containing such a path can be paid, it also tests
the peeling of dummy hops by the receiver.

itest/list_on_test.go

@@ -590,6 +590,10 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "mpp to single blinded path",
 		TestFunc: testMPPToSingleBlindedPath,
 	},
+	{
+		Name:     "route blinding dummy hops",
+		TestFunc: testBlindedRouteDummyHops,
+	},
 	{
 		Name:     "removetx",
 		TestFunc: testRemoveTx,