lrwn: Implement v1 applayer multicast setup structs.

lrwn/src/applayer/mod.rs

@@ -1,6 +1,7 @@
 use anyhow::Result;
 
 pub mod clocksync;
+pub mod multicastsetup;
 
 pub trait PayloadCodec<Struct = Self> {
     fn decode(b: &[u8]) -> Result<Struct>;

lrwn/src/applayer/multicastsetup/mod.rs

@@ -0,0 +1 @@
+pub mod v1;