refactor(forks): Refactor extract fork until from logic, add BPO forks by default

[marioevz]

🗒️ Description

Refactor Validity Marker Logic in src/pytest_plugins/forks/forks.py

Add Fork Adapters to ethereum_test_forks.helpers

Adds pydantic adapters to Fork and ForkSet.

This allows to add click parameters that automatically parse a comma-separated string of fork names into the appropriate fork type.

Add get_selected_fork_set to ethereum_test_forks.helpers

Extracts the --fork, --until and --from selector logic from the forks pytest plugin into ethereum_test_forks, in order to reuse this logic in other tools (e.g. #2045).

Refactor ValidityMarker Logic in Forks Pytest Plugin

Refactors the logic to select the forks a test should run in given a list of validity markers.

🔗 Related Issues or PRs

N/A.

✅ Checklist

• All: Ran fast tox checks to avoid unnecessary CI fails, see also Code Standards and Enabling Pre-commit Checks:

  uvx --with=tox-uv tox -e lint,typecheck,spellcheck,markdownlint

• All: PR title adheres to the repo standard - it will be used as the squash commit message and should start type(scope):.
• All: Considered adding an entry to CHANGELOG.md.
• All: Considered updating the online docs in the ./docs/ directory.