new(tests): Identity precompile test

[marioevz]

🗒️ Description

Adds a test for the identity precompile based on this https://github.com/ethereum/go-ethereum/blob/master/docs/postmortems/2021-08-22-split-postmortem.md

Also adds a new variant that can be filled for EOF EXT*CALL opcodes .

🔗 Related Issues

✅ 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.

[marioevz]

@shemnon I was reviewing your memory expansion tests and remembered this case, so decided to add a test that can be filled for the EXT*CALL opcodes in test_identity_return_buffer_modify, let me know what you think.