Fix: Ensure Isthmus withdrawals root validation for non-canonical parent state in Optimism engine

[petrokamin10]

Previously, when state_by_block_hash failed, the validator returned Ok(()), effectively skipping withdrawals root verification for blocks whose parent was not yet in the canonical chain.
This created a window where blocks could bypass a critical consensus check during reorgs or while processing non-canonical branches.

• Fix OpEngineValidator::validate_block_post_execution_with_hashed_state to always validate the Isthmus withdrawals root, even when the parent block state is not yet canonical.
• Resolve state lookups by first trying historical state and then pending state; if neither is available, return a consensus error instead of silently accepting the block.

[mattsse]

this is a bit more tricky, and the current design for this is a bit of a footgun

I guess we'd need to extend this with like parent_state: BlockState to alway provide access to any parent state

[mattsse]

this is a bit more tricky than that because technically, the block's parent isn't necessarily part of the canonical chain yet
in which case we'd fail to resolve it via the provider which only gives access to the canonical chain + pending block

so this change doesnt fully cover all scenarios, but in almost all cases we ca n assume that this is the case

[mattsse]

Closing this PR as op-reth has been moved to its own repository. See #21532 and the updated README for the new location. If this is still relevant, please re-open in the new op-reth repository. 🙏