Add block_gossip Beacon API events (#5864)

* Add bls event

* Update events and types

* Add bls in event

* Event bls

* tests..rs

* change order

* another tests.rs

* Signed BLS

* Revert "another tests.rs"

This reverts commit 7f54e9c1ce.

* Revert "Signed BLS"

This reverts commit 1146bc734b.

* withdrawal_keyparis

* Fix genesis

* block gossip

* Add definition for BlockGossip

* Fix block gossip

* Tests.rs

* Update block and events

* Add bls event

* Event bls

* tests..rs

* change order

* another tests.rs

* Signed BLS

* Revert "another tests.rs"

This reverts commit 7f54e9c1ce.

* Revert "Signed BLS"

This reverts commit 1146bc734b.

* block gossip

* Add definition for BlockGossip

* Fix block gossip

* Tests.rs

* Update block and events

* Merge branch 'BeaconAPI-events-block-gossip' of https://github.com/chong-he/lighthouse into BeaconAPI-events-block-gossip

* Remove tests

* Tests.rs

* Tests.rs

* Tests.rs

* Tests similar to block event

* Update common/eth2/src/types.rs

Co-authored-by: Michael Sproul <micsproul@gmail.com>

* Merge remote-tracking branch 'origin/unstable' into BeaconAPI-events-block-gossip

* Fix tests

beacon_node/beacon_chain/src/block_verification.rs

@@ -67,7 +67,7 @@ use crate::{
     metrics, BeaconChain, BeaconChainError, BeaconChainTypes,
 };
 use derivative::Derivative;
-use eth2::types::{EventKind, PublishBlockRequest};
+use eth2::types::{BlockGossip, EventKind, PublishBlockRequest};
 use execution_layer::PayloadStatus;
 pub use fork_choice::{AttestationFromBlock, PayloadVerificationStatus};
 use parking_lot::RwLockReadGuard;
@@ -974,6 +974,16 @@ impl<T: BeaconChainTypes> GossipVerifiedBlock<T> {
         // Validate the block's execution_payload (if any).
         validate_execution_payload_for_gossip(&parent_block, block.message(), chain)?;
 
+        // Beacon API block_gossip events
+        if let Some(event_handler) = chain.event_handler.as_ref() {
+            if event_handler.has_block_gossip_subscribers() {
+                event_handler.register(EventKind::BlockGossip(Box::new(BlockGossip {
+                    slot: block.slot(),
+                    block: block_root,
+                })));
+            }
+        }
+
         // Having checked the proposer index and the block root we can cache them.
         let consensus_context = ConsensusContext::new(block.slot())
             .set_current_block_root(block_root)