new(tests): Blockhash at 255/256/257 (ethereum/execution-specs#374)

[codeofcarson]

🗒️ Description

This adds tests designed to test the BLOCKHASH opcode for when there are 255, 256, and 257 blocks in the chain.

Filled with https://github.com/ethereum/execution-specs#9b95554a88d2a8485f8180254d0f6a493a593fda

🔗 Related Issues

This is actually issue (ethereum/execution-specs#374) in the execution-specs

✅ Checklist

• All: Set appropriate labels for the changes.
• All: Considered squashing commits to improve commit history.
• All: Added an entry to CHANGELOG.md.
• All: Considered updating the online docs in the ./docs/ directory.
• Tests: All converted JSON/YML tests from ethereum/tests have been added to converted-ethereum-tests.txt.
• Tests: A PR with removal of converted JSON/YML tests from ethereum/tests have been opened.
• Tests: Included the type and version of evm t8n tool used to locally execute test cases: e.g., ref with commit hash or geth 1.13.1-stable-3f40e65.
• Tests: Ran mkdocs serve locally and verified the auto-generated docs for new tests in the Test Case Reference are correctly formatted.

I will add the CHANGELOG update before this gets merged after review.

Do I need to update the docs in the codebase for this one too?

[codeofcarson]

For this one I sneakily grabbed the hashes off of the outputs for the tests when I ran them. You won't be able to do that with future forks right? Is there a way that it could be computed on the fly?