lnwire: define NodeAnnouncement2

In this commit, the lnwire.NodeAnnouncement2 type is defined. This will
be used to represent the `node_announcement_2` message used in the
Gossip 2 (1.75) protocol.

lnwire/fuzz_test.go

@@ -244,6 +244,30 @@ func FuzzNodeAnnouncement(f *testing.F) {
 	})
 }
 
+func FuzzNodeAnnouncement2(f *testing.F) {
+	f.Fuzz(func(t *testing.T, data []byte) {
+		// We can't use require.Equal for Features, since we consider
+		// the empty map and nil to be equivalent.
+		assertEq := func(t *testing.T, x, y any) {
+			require.IsType(t, &NodeAnnouncement2{}, x)
+			first, _ := x.(*NodeAnnouncement2)
+			require.IsType(t, &NodeAnnouncement2{}, y)
+			second, _ := y.(*NodeAnnouncement2)
+
+			require.True(
+				t,
+				first.Features.Val.Equals(&second.Features.Val),
+			)
+			first.Features.Val = *NewRawFeatureVector()
+			second.Features.Val = *NewRawFeatureVector()
+
+			require.Equal(t, first, second)
+		}
+
+		wireMsgHarnessCustom(t, data, MsgNodeAnnouncement2, assertEq)
+	})
+}
+
 func FuzzOpenChannel(f *testing.F) {
 	f.Fuzz(func(t *testing.T, data []byte) {
 		// We can't use require.Equal for UpfrontShutdownScript, since