feat(fill): add a config file for the eels resolver to pin versions

[danceratopz]

🗒️ Description

Currently, as EEST doesn't configure the EELS resolver, it takes the HEAD of execution-specs master for all forks. This exposes EEST to any issues that make it to execution-specs master. This PR aims to eliminate this risk and improve reporting the EELS version used to fill forks:

• Add a config file eels_resolutions.json that pins the ethereum/execution-specs main branch reference for deployed and Prague forks, see the ethereum-spec-evm-resolver README.
• Use the eels_resolutions.json in fill and the framework tests automatically by setting the EELS_RESOLUTIONS_FILE envvar in an eels_resolver plugin. The value will not be clobbered, however, if the user has manually set EELS_RESOLUTIONS_FILE.
• Report the resolutions file used in the pytest report header and metadata (metadata plugin).
• Copy the resolutions file to the fixture's .meta folder (to verify fixture origin in releases, for example).

🔗 Related Issues

#792

✅ 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]

LGTM, thanks!