Silky smooth discovery (#1274)

* Initial structural re-write

* Improving discovery update and correcting attestation service logic

* Rework discovery.mod

* Handling lifetimes of query futures

* Discovery update first draft

* format fixes

* Stabalise discv5 update

* Formatting corrections

* Limit FindPeers queries and bug correction

* Update to stable release discv5

* Remove unnecessary pin

* formatting

beacon_node/src/lib.rs

@@ -82,6 +82,8 @@ impl<E: EthSpec> ProductionBeaconNode<E> {
         let db_path = client_config.create_db_path()?;
         let freezer_db_path_res = client_config.create_freezer_db_path();
 
+        let executor = context.executor.clone();
+
         let builder = ClientBuilder::new(context.eth_spec_instance.clone())
             .runtime_context(context)
             .chain_spec(spec)
@@ -119,6 +121,9 @@ impl<E: EthSpec> ProductionBeaconNode<E> {
             .system_time_slot_clock()?
             .tee_event_handler(client_config.websocket_server.clone())?;
 
+        // Inject the executor into the discv5 network config.
+        client_config.network.discv5_config.executor = Some(Box::new(executor));
+
         let builder = builder
             .build_beacon_chain()?
             .network(&mut client_config.network)?