Update the EF spec tests to v1.6.0-beta.1
There are a few new light client tests (which we pass), and some for progressive containers, which we haven't implemented (we ignore them).
Co-Authored-By: Michael Sproul <michael@sigmaprime.io>
This PR adds the ability to download [nightly reference tests from the consensus-specs repo](https://github.com/ethereum/consensus-specs/actions/workflows/generate_vectors.yml). This will be used by spec maintainers to ensure that there are no unexpected test failures prior to new releases. Also, we will keep track of test compliance with [this website](https://jtraglia.github.io/nyx/); eventually this will be integrated into Hive.
* A new script (`download_test_vectors.sh`) is added to handle downloads.
* The logic for downloading GitHub artifacts is a bit complex.
* Rename the variables which store test versions:
* `TESTS_TAG` to `CONSENSUS_SPECS_TEST_VERSION`.
* `BLS_TEST_TAG` to `BLS_TEST_VERSION`, for consistency.
* Delete tarballs after extracting them.
* I see no need to keep these; they just use extra disk.
* Consolidate `clean` rules into a single rule.
* Do `clean` prior to downloading/extracting tests.
* Remove `CURL` variable with GitHub token; don't need it for downloading releases.
* Do `mkdir -p` when creating directories.
* Probably more small stuff...
