Add Gloas boilerplate (#7728)

Adds the required boilerplate code for the Gloas (Glamsterdam) hard fork. This allows PRs testing Gloas-candidate features to test fork transition.

This also includes de-duplication of post-Bellatrix readiness notifiers from #6797 (credit to @dapplion)

consensus/state_processing/src/upgrade/gloas.rs

@@ -0,0 +1,93 @@
+use std::mem;
+use types::{BeaconState, BeaconStateError as Error, BeaconStateGloas, ChainSpec, EthSpec, Fork};
+
+/// Transform a `Fulu` state into a `Gloas` state.
+pub fn upgrade_to_gloas<E: EthSpec>(
+    pre_state: &mut BeaconState<E>,
+    spec: &ChainSpec,
+) -> Result<(), Error> {
+    let post = upgrade_state_to_gloas(pre_state, spec)?;
+
+    *pre_state = post;
+
+    Ok(())
+}
+
+pub fn upgrade_state_to_gloas<E: EthSpec>(
+    pre_state: &mut BeaconState<E>,
+    spec: &ChainSpec,
+) -> Result<BeaconState<E>, Error> {
+    let epoch = pre_state.current_epoch();
+    let pre = pre_state.as_fulu_mut()?;
+    // Where possible, use something like `mem::take` to move fields from behind the &mut
+    // reference. For other fields that don't have a good default value, use `clone`.
+    //
+    // Fixed size vectors get cloned because replacing them would require the same size
+    // allocation as cloning.
+    let post = BeaconState::Gloas(BeaconStateGloas {
+        // Versioning
+        genesis_time: pre.genesis_time,
+        genesis_validators_root: pre.genesis_validators_root,
+        slot: pre.slot,
+        fork: Fork {
+            previous_version: pre.fork.current_version,
+            current_version: spec.gloas_fork_version,
+            epoch,
+        },
+        // History
+        latest_block_header: pre.latest_block_header.clone(),
+        block_roots: pre.block_roots.clone(),
+        state_roots: pre.state_roots.clone(),
+        historical_roots: mem::take(&mut pre.historical_roots),
+        // Eth1
+        eth1_data: pre.eth1_data.clone(),
+        eth1_data_votes: mem::take(&mut pre.eth1_data_votes),
+        eth1_deposit_index: pre.eth1_deposit_index,
+        // Registry
+        validators: mem::take(&mut pre.validators),
+        balances: mem::take(&mut pre.balances),
+        // Randomness
+        randao_mixes: pre.randao_mixes.clone(),
+        // Slashings
+        slashings: pre.slashings.clone(),
+        // `Participation
+        previous_epoch_participation: mem::take(&mut pre.previous_epoch_participation),
+        current_epoch_participation: mem::take(&mut pre.current_epoch_participation),
+        // Finality
+        justification_bits: pre.justification_bits.clone(),
+        previous_justified_checkpoint: pre.previous_justified_checkpoint,
+        current_justified_checkpoint: pre.current_justified_checkpoint,
+        finalized_checkpoint: pre.finalized_checkpoint,
+        // Inactivity
+        inactivity_scores: mem::take(&mut pre.inactivity_scores),
+        // Sync committees
+        current_sync_committee: pre.current_sync_committee.clone(),
+        next_sync_committee: pre.next_sync_committee.clone(),
+        // Execution
+        latest_execution_payload_header: pre.latest_execution_payload_header.upgrade_to_gloas(),
+        // Capella
+        next_withdrawal_index: pre.next_withdrawal_index,
+        next_withdrawal_validator_index: pre.next_withdrawal_validator_index,
+        historical_summaries: pre.historical_summaries.clone(),
+        // Electra
+        deposit_requests_start_index: pre.deposit_requests_start_index,
+        deposit_balance_to_consume: pre.deposit_balance_to_consume,
+        exit_balance_to_consume: pre.exit_balance_to_consume,
+        earliest_exit_epoch: pre.earliest_exit_epoch,
+        consolidation_balance_to_consume: pre.consolidation_balance_to_consume,
+        earliest_consolidation_epoch: pre.earliest_consolidation_epoch,
+        pending_deposits: pre.pending_deposits.clone(),
+        pending_partial_withdrawals: pre.pending_partial_withdrawals.clone(),
+        pending_consolidations: pre.pending_consolidations.clone(),
+        // Caches
+        total_active_balance: pre.total_active_balance,
+        progressive_balances_cache: mem::take(&mut pre.progressive_balances_cache),
+        committee_caches: mem::take(&mut pre.committee_caches),
+        pubkey_cache: mem::take(&mut pre.pubkey_cache),
+        exit_cache: mem::take(&mut pre.exit_cache),
+        slashings_cache: mem::take(&mut pre.slashings_cache),
+        epoch_cache: mem::take(&mut pre.epoch_cache),
+        proposer_lookahead: mem::take(&mut pre.proposer_lookahead),
+    });
+    Ok(post)
+}