Make Payee::pubkey pub.

`Payee` is expected to be used by users to get routes for payment
retries, potentially with their own router. Thus, its helpful if it
is pub, even if it is redundant with the last hop in the `path`
field in `Events::PaymentPathFailed`.

Author: TheBlueMatt

lightning/src/routing/router.rs

@@ -156,7 +156,7 @@ impl_writeable_tlv_based!(PaymentPathRetry, {
 #[derive(Clone, Debug)]
 pub struct Payee {
 	/// The node id of the payee.
-	pubkey: PublicKey,
+	pub pubkey: PublicKey,
 
 	/// Features supported by the payee.
 	///