🐞(gentest): generate test cases as a state_test for single transactions

[danceratopz]

Currently, gentest generates test cases in the blockchain_test format.

However, if a test case can be expressed as a state_test, state_test is the preferred format. This is because:

• fill will additionally generate a blockchain_test fixture from state-tests (consisting of one block and one transaction).
• The state_test format provides more targeted testing, as it does not invoke a client's block building machinery (for exception tests, this can lead to false positives, see Zero max_fee_per_blob_gas test is ineffective #343).

Bonus points for adding this rationale to EEST's HTML documentation in "Writing Tests" 🙂.

[raxhvl]

Picking this up next.