docs: some ideas on moving ./tests to ethereum/execution-specs

[danceratopz]

🗒️ Description

Just some thoughts about what we envision "The Merge" (or depending on your POV, the "The Move" 😆) should look like and what it requires.

Not complete by any means, just thought it could help serve as a basis for discussion!

Feel free to add comments to this PR or in Discord!

Background

For those unfamiliar with the discussion: The plan is to move the EL client test cases in ./tests/ to ethereum/execution-specs.

Here's the main motivation for this change (these are overlapping):

1. Spec and tests versioned together. Less ambiguous.
2. EIP authors/implementers:
   i. Need only concern themselves with one repo.
   ii. Can directly & very easily add basic tests to sanity check their implementations.
3. This removes the chicken & egg problem when testing the spec: To test an EELS branch you need an EEST release which needs an EELS branch ♻️.
4. Simplifies tooling and debugging: Removes the need for petertdavies/ethereum-spec-evm-resolver, which currently allows us to fill multiple EELS implementations from multiple repos/branches within one test session.

🔗 Related Issues

Current sub-tasks:

• chore(packaging): publish hive.py as a package #1560
• chore(packaging): make eest a publishable package #1565

There's no plan to merge this PR - but we can update the doc with comments to gain a shared understanding!

[winsvega]

So the execution-spec-tests will be used as a package in execution-specs ?

[danceratopz]

So the execution-spec-tests will be used as a package in execution-specs ?

Yes.