Single attestation "Full" implementation (#7444)

#6970


  This allows for us to receive `SingleAttestation` over gossip and process it without converting. There is still a conversion to `Attestation` as a final step in the attestation verification process, but by then the `SingleAttestation` is fully verified.

I've also fully removed the `submitPoolAttestationsV1` endpoint as its been deprecated

I've also pre-emptively deprecated supporting `Attestation` in `submitPoolAttestationsV2` endpoint. See here for more info: https://github.com/ethereum/beacon-APIs/pull/531

I tried to the minimize the diff here by only making the "required" changes. There are some unnecessary complexities with the way we manage the different attestation verification wrapper types. We could probably consolidate this to one wrapper type and refactor this even further. We could leave that to a separate PR if we feel like cleaning things up in the future.

Note that I've also updated the test harness to always submit `SingleAttestation` regardless of fork variant. I don't see a problem in that approach and it allows us to delete more code :)

common/eth2/src/lib.rs

@@ -18,7 +18,6 @@ use self::mixin::{RequestAccept, ResponseOptional};
 use self::types::{Error as ResponseError, *};
 use ::types::beacon_response::ExecutionOptimisticFinalizedBeaconResponse;
 use derivative::Derivative;
-use either::Either;
 use futures::Stream;
 use futures_util::StreamExt;
 use libp2p_identity::PeerId;
@@ -1434,29 +1433,10 @@ impl BeaconNodeHttpClient {
             .map(|opt| opt.map(BeaconResponse::ForkVersioned))
     }
 
-    /// `POST v1/beacon/pool/attestations`
-    pub async fn post_beacon_pool_attestations_v1<E: EthSpec>(
-        &self,
-        attestations: &[Attestation<E>],
-    ) -> Result<(), Error> {
-        let mut path = self.eth_path(V1)?;
-
-        path.path_segments_mut()
-            .map_err(|()| Error::InvalidUrl(self.server.clone()))?
-            .push("beacon")
-            .push("pool")
-            .push("attestations");
-
-        self.post_with_timeout(path, &attestations, self.timeouts.attestation)
-            .await?;
-
-        Ok(())
-    }
-
     /// `POST v2/beacon/pool/attestations`
     pub async fn post_beacon_pool_attestations_v2<E: EthSpec>(
         &self,
-        attestations: Either<Vec<Attestation<E>>, Vec<SingleAttestation>>,
+        attestations: Vec<SingleAttestation>,
         fork_name: ForkName,
     ) -> Result<(), Error> {
         let mut path = self.eth_path(V2)?;
@@ -1467,26 +1447,13 @@ impl BeaconNodeHttpClient {
             .push("pool")
             .push("attestations");
 
-        match attestations {
-            Either::Right(attestations) => {
-                self.post_with_timeout_and_consensus_header(
-                    path,
-                    &attestations,
-                    self.timeouts.attestation,
-                    fork_name,
-                )
-                .await?;
-            }
-            Either::Left(attestations) => {
-                self.post_with_timeout_and_consensus_header(
-                    path,
-                    &attestations,
-                    self.timeouts.attestation,
-                    fork_name,
-                )
-                .await?;
-            }
-        };
+        self.post_with_timeout_and_consensus_header(
+            path,
+            &attestations,
+            self.timeouts.attestation,
+            fork_name,
+        )
+        .await?;
 
         Ok(())
     }