Gloas cold DB (#8991)

Closes:

- https://github.com/sigp/lighthouse/issues/8958


  - Update the `HotColdStore` to handle storage of cold states.
- Update `BeaconSnapshot` to hold the execution envelope. This is required to make `chain_dump`-related checks sane, and will be generally useful (see: https://github.com/sigp/lighthouse/issues/8956).
- Bug fix in the `BlockReplayer` for the case where the starting state is already `Full` (we should not try to apply another payload). This happens on the cold DB path because we try to replay from the closest cached state (which is often full).
- Update `test_gloas_hot_state_hierarchy` to cover the cold DB migration.


Co-Authored-By: Michael Sproul <michael@sigmaprime.io>

Co-Authored-By: Michael Sproul <michaelsproul@users.noreply.github.com>

beacon_node/beacon_chain/tests/store_tests.rs

@@ -5599,6 +5599,7 @@ async fn test_gloas_block_and_envelope_storage_generic(
             "slot = {slot}"
         );
     }
+    check_db_invariants(&harness);
 }
 
 /// Test that Pending and Full states have the correct payload status through round-trip
@@ -5666,6 +5667,7 @@ async fn test_gloas_state_payload_status() {
 
         state = full_state;
     }
+    check_db_invariants(&harness);
 }
 
 /// Test block replay with and without envelopes.
@@ -5805,6 +5807,7 @@ async fn test_gloas_block_replay_with_envelopes() {
         replayed_full, expected_full,
         "replayed full state should match stored full state"
     );
+    check_db_invariants(&harness);
 }
 
 /// Test the hot state hierarchy with Full states stored as ReplayFrom.
@@ -5822,7 +5825,7 @@ async fn test_gloas_hot_state_hierarchy() {
     // 40 slots covers 5 epochs.
     let num_blocks = E::slots_per_epoch() * 5;
     // TODO(gloas): enable finalisation by increasing this threshold
-    let some_validators = (0..LOW_VALIDATOR_COUNT / 2).collect::<Vec<_>>();
+    let some_validators = (0..LOW_VALIDATOR_COUNT).collect::<Vec<_>>();
 
     let (genesis_state, _genesis_state_root) = harness.get_current_state_and_root();
 
@@ -5886,6 +5889,7 @@ async fn test_gloas_hot_state_hierarchy() {
     // Verify chain dump and iterators work with Gloas states.
     check_chain_dump(&harness, num_blocks + 1);
     check_iterators(&harness);
+    check_db_invariants(&harness);
 }
 
 /// Check that the HotColdDB's split_slot is equal to the start slot of the last finalized epoch.