Add tests that verify MDBX and RocksDB produce identical results for
history lookups using EitherWriter and EitherReader abstractions.
These tests address joshieDo's PR review feedback to use the Either*
types instead of duplicating backend-specific code.
- Add account_history_info and storage_history_info methods to EitherReader
- Add HistoryQuery struct and run_*_history_scenario helper functions
- Test scenarios: single shard, multiple shards, no history, pruning boundary