use state cache to optimise historical state lookup (#4228)

## Issue Addressed

#3873

## Proposed Changes

add a cache to optimise historical state lookup.

## Additional Info

N/A


Co-authored-by: Michael Sproul <micsproul@gmail.com>

book/src/database-migrations.md

@@ -92,6 +92,7 @@ curl "http://localhost:5052/lighthouse/database/info"
     "slots_per_restore_point": 8192,
     "slots_per_restore_point_set_explicitly": true,
     "block_cache_size": 5,
+    "historic_state_cache_size": 1,
     "compact_on_init": false,
     "compact_on_prune": true
   }