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 :)

beacon_node/beacon_processor/src/lib.rs

@@ -63,7 +63,7 @@ use tokio::sync::mpsc;
 use tokio::sync::mpsc::error::TrySendError;
 use tracing::{debug, error, trace, warn};
 use types::{
-    Attestation, BeaconState, ChainSpec, EthSpec, Hash256, RelativeEpoch, SignedAggregateAndProof,
+    BeaconState, ChainSpec, EthSpec, Hash256, RelativeEpoch, SignedAggregateAndProof,
     SingleAttestation, Slot, SubnetId,
 };
 use work_reprocessing_queue::{
@@ -557,32 +557,23 @@ pub enum BlockingOrAsync {
     Blocking(BlockingFn),
     Async(AsyncFn),
 }
-pub type GossipAttestationBatch<E> = Vec<GossipAttestationPackage<Attestation<E>>>;
+pub type GossipAttestationBatch = Vec<GossipAttestationPackage<SingleAttestation>>;
 
 /// Indicates the type of work to be performed and therefore its priority and
 /// queuing specifics.
 pub enum Work<E: EthSpec> {
     GossipAttestation {
-        attestation: Box<GossipAttestationPackage<Attestation<E>>>,
-        process_individual: Box<dyn FnOnce(GossipAttestationPackage<Attestation<E>>) + Send + Sync>,
-        process_batch: Box<dyn FnOnce(GossipAttestationBatch<E>) + Send + Sync>,
-    },
-    // Attestation requiring conversion before processing.
-    //
-    // For now this is a `SingleAttestation`, but eventually we will switch this around so that
-    // legacy `Attestation`s are converted and the main processing pipeline operates on
-    // `SingleAttestation`s.
-    GossipAttestationToConvert {
         attestation: Box<GossipAttestationPackage<SingleAttestation>>,
         process_individual:
             Box<dyn FnOnce(GossipAttestationPackage<SingleAttestation>) + Send + Sync>,
+        process_batch: Box<dyn FnOnce(GossipAttestationBatch) + Send + Sync>,
     },
     UnknownBlockAttestation {
         process_fn: BlockingFn,
     },
     GossipAttestationBatch {
-        attestations: GossipAttestationBatch<E>,
-        process_batch: Box<dyn FnOnce(GossipAttestationBatch<E>) + Send + Sync>,
+        attestations: GossipAttestationBatch,
+        process_batch: Box<dyn FnOnce(GossipAttestationBatch) + Send + Sync>,
     },
     GossipAggregate {
         aggregate: Box<GossipAggregatePackage<E>>,
@@ -712,7 +703,6 @@ impl<E: EthSpec> Work<E> {
     fn to_type(&self) -> WorkType {
         match self {
             Work::GossipAttestation { .. } => WorkType::GossipAttestation,
-            Work::GossipAttestationToConvert { .. } => WorkType::GossipAttestationToConvert,
             Work::GossipAttestationBatch { .. } => WorkType::GossipAttestationBatch,
             Work::GossipAggregate { .. } => WorkType::GossipAggregate,
             Work::GossipAggregateBatch { .. } => WorkType::GossipAggregateBatch,
@@ -1330,9 +1320,6 @@ impl<E: EthSpec> BeaconProcessor<E> {
                         match work {
                             _ if can_spawn => self.spawn_worker(work, idle_tx),
                             Work::GossipAttestation { .. } => attestation_queue.push(work),
-                            Work::GossipAttestationToConvert { .. } => {
-                                attestation_to_convert_queue.push(work)
-                            }
                             // Attestation batches are formed internally within the
                             // `BeaconProcessor`, they are not sent from external services.
                             Work::GossipAttestationBatch { .. } => crit!(
@@ -1578,12 +1565,6 @@ impl<E: EthSpec> BeaconProcessor<E> {
             } => task_spawner.spawn_blocking(move || {
                 process_individual(*attestation);
             }),
-            Work::GossipAttestationToConvert {
-                attestation,
-                process_individual,
-            } => task_spawner.spawn_blocking(move || {
-                process_individual(*attestation);
-            }),
             Work::GossipAttestationBatch {
                 attestations,
                 process_batch,