Store EntropySource in DefaultRouter instead of passing it

...as an arg to `Router`. Passing an `EntropySource` around all
the time is a bit strange as the `Router` may or may not actually
use it, and the `DefaultRouter` can just as easily store it.

Author: TheBlueMatt

lightning/src/onion_message/functional_tests.rs

@@ -34,6 +34,8 @@ use core::ops::Deref;
 
 use crate::prelude::*;
 
+use core::ops::Deref;
+
 struct MessengerNode {
 	node_id: PublicKey,
 	privkey: SecretKey,

lightning/src/util/test_utils.rs

@@ -65,6 +65,7 @@ use crate::io;
 use crate::prelude::*;
 use core::cell::RefCell;
 use core::time::Duration;
+use core::ops::Deref;
 use crate::sync::{Mutex, Arc};
 use core::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
 use core::mem;