Publish built fixtures to a standalone repository

[marioevz]

• Add a step to .github/workflows/fixtures_feature.yaml and .github/workflows/fixtures.yaml to also push the built fixtures to a separate repository.
• Each feature-built fixtures could live in a separate branch of this repository
• We could explore either building for each PR merged and push that to the main branch, or having stable version of the repository be the main branch.

[winsvega]

I would vote to use ethereum/tests repo for it. Just overwrite over it, move current develop to a separate branch or legacy tests repo

[fselmo]

If I understand correctly, moving the current state of ethereum/tests into /LegacyTests as the submodule and having the branches in ethereum/tests transition to static EEST-filled json files would allow consumers to pull from both EEST and ethereum/tests jsons with one git tag as the version.

I think this would be ideal, at least while conversion of the legacy tests to EEST is still in progress. Unless there's a better way that I'm not seeing to ensure full test coverage for consumers during the transition.