Event-based block lookup tests (#5534)

* WIP

* Initial working version of new sync tests.

* Remove sync traits and fix lints.

* Reduce internal method visibility and make test method instead. Remove extra beacon chain harness instance created in tests.

* Improve `SyncTester` api.

* Fix lint.

* Test example

* Lookup tests using rig

* Tests should interface with events only

* lint

* Skip deneb test pre-deneb

* Add more assertions

* Remove logging changes

* Address @jimmygchen comments

* Merge branch 'unstable' of https://github.com/sigp/lighthouse into bn-p2p-tests

* remove unused assertions

* fix lint

beacon_node/lighthouse_network/src/peer_manager/peerdb.rs

@@ -1,3 +1,4 @@
+use crate::discovery::CombinedKey;
 use crate::{metrics, multiaddr::Multiaddr, types::Subnet, Enr, Gossipsub, PeerId};
 use peer_info::{ConnectionDirection, PeerConnectionStatus, PeerInfo};
 use rand::seq::SliceRandom;
@@ -671,6 +672,20 @@ impl<E: EthSpec> PeerDB<E> {
         );
     }
 
+    /// Updates the connection state. MUST ONLY BE USED IN TESTS.
+    pub fn __add_connected_peer_testing_only(&mut self, peer_id: &PeerId) -> Option<BanOperation> {
+        let enr_key = CombinedKey::generate_secp256k1();
+        let enr = Enr::builder().build(&enr_key).unwrap();
+        self.update_connection_state(
+            peer_id,
+            NewConnectionState::Connected {
+                enr: Some(enr),
+                seen_address: Multiaddr::empty(),
+                direction: ConnectionDirection::Outgoing,
+            },
+        )
+    }
+
     /// The connection state of the peer has been changed. Modify the peer in the db to ensure all
     /// variables are in sync with libp2p.
     /// Updating the state can lead to a `BanOperation` which needs to be processed via the peer