Changes for fusaka-devnet-1 (#7559)

Changes for [fusaka-devnet-1](https://notes.ethereum.org/@ethpandaops/fusaka-devnet-1)


  [Consensus Specs v1.6.0-alpha.1](https://github.com/ethereum/consensus-specs/pull/4346)
* [EIP-7917: Deterministic Proposer Lookahead](https://eips.ethereum.org/EIPS/eip-7917)
* [EIP-7892: Blob Parameter Only Hardforks](https://eips.ethereum.org/EIPS/eip-7892)

consensus/state_processing/src/per_epoch_processing/single_pass.rs

@@ -19,7 +19,7 @@ use types::{
     milhouse::Cow,
     ActivationQueue, BeaconState, BeaconStateError, ChainSpec, Checkpoint, DepositData, Epoch,
     EthSpec, ExitCache, ForkName, List, ParticipationFlags, PendingDeposit,
-    ProgressiveBalancesCache, RelativeEpoch, Unsigned, Validator,
+    ProgressiveBalancesCache, RelativeEpoch, Unsigned, Validator, Vector,
 };
 
 pub struct SinglePassConfig {
@@ -30,6 +30,7 @@ pub struct SinglePassConfig {
     pub pending_deposits: bool,
     pub pending_consolidations: bool,
     pub effective_balance_updates: bool,
+    pub proposer_lookahead: bool,
 }
 
 impl Default for SinglePassConfig {
@@ -48,6 +49,7 @@ impl SinglePassConfig {
             pending_deposits: true,
             pending_consolidations: true,
             effective_balance_updates: true,
+            proposer_lookahead: true,
         }
     }
 
@@ -60,6 +62,7 @@ impl SinglePassConfig {
             pending_deposits: false,
             pending_consolidations: false,
             effective_balance_updates: false,
+            proposer_lookahead: false,
         }
     }
 }
@@ -460,9 +463,43 @@ pub fn process_epoch_single_pass<E: EthSpec>(
             next_epoch_cache.into_epoch_cache(next_epoch_activation_queue, spec)?;
     }
 
+    if conf.proposer_lookahead && fork_name.fulu_enabled() {
+        process_proposer_lookahead(state, spec)?;
+    }
+
     Ok(summary)
 }
 
+// TOOO(EIP-7917): use balances cache
+pub fn process_proposer_lookahead<E: EthSpec>(
+    state: &mut BeaconState<E>,
+    spec: &ChainSpec,
+) -> Result<(), Error> {
+    let mut lookahead = state.proposer_lookahead()?.clone().to_vec();
+
+    // Shift out proposers in the first epoch
+    lookahead.copy_within((E::slots_per_epoch() as usize).., 0);
+
+    let next_epoch = state
+        .current_epoch()
+        .safe_add(spec.min_seed_lookahead.as_u64())?
+        .safe_add(1)?;
+    let last_epoch_proposers = state.get_beacon_proposer_indices(next_epoch, spec)?;
+
+    // Fill in the last epoch with new proposer indices
+    let last_epoch_start = E::proposer_lookahead_slots().safe_sub(E::slots_per_epoch() as usize)?;
+    for (i, proposer) in last_epoch_proposers.into_iter().enumerate() {
+        let index = last_epoch_start.safe_add(i)?;
+        *lookahead
+            .get_mut(index)
+            .ok_or(Error::ProposerLookaheadOutOfBounds(index))? = proposer as u64;
+    }
+
+    *state.proposer_lookahead_mut()? = Vector::new(lookahead)?;
+
+    Ok(())
+}
+
 fn process_single_inactivity_update(
     inactivity_score: &mut Cow<u64>,
     validator_info: &ValidatorInfo,