Add contribution and proof event (#2527)

## Issue Addressed

N/A

## Proposed Changes

Add the new ContributionAndProof event: https://github.com/ethereum/beacon-APIs/pull/158

## Additional Info

N/A

Co-authored-by: realbigsean <seananderson33@gmail.com>

beacon_node/beacon_chain/src/test_utils.rs

@@ -351,7 +351,7 @@ where
             .chain_config(chain_config)
             .event_handler(Some(ServerSentEventHandler::new_with_capacity(
                 log.clone(),
-                1,
+                5,
             )))
             .monitor_validators(true, vec![], log);