Offloading KZG Proof Computation from the beacon node (#7117)

Addresses #7108

- Add EL integration for `getPayloadV5` and `getBlobsV2`
- Offload proof computation and use proofs from EL RPC APIs

beacon_node/beacon_chain/src/early_attester_cache.rs

@@ -74,10 +74,6 @@ impl<E: EthSpec> EarlyAttesterCache<E> {
             AvailableBlockData::NoData => (None, None),
             AvailableBlockData::Blobs(blobs) => (Some(blobs.clone()), None),
             AvailableBlockData::DataColumns(data_columns) => (None, Some(data_columns.clone())),
-            // TODO(das): Once the columns are received, they will not be available in
-            // the early attester cache. If someone does a query to us via RPC we
-            // will get downscored.
-            AvailableBlockData::DataColumnsRecv(_) => (None, None),
         };
 
         let item = CacheItem {