isthmus: tests of state transition with operator fees

[sebastianst]

#388 implements the operator fee. It doesn't add tests of the STF with operator fees enabled. Test coverage of it only exists indirectly in the monorepo (see ethereum-optimism/optimism#12166).

If possible, it would be good to identify existing geth tests that we could parameterize to run with non-zero operator fee params so that there are also tests of the operator fee implementation in op-geth itself.

The test should also cover the case of non-zero state refunds. There were discrepancies in the Go and Rust implementations before, so we don't want a regression to slip unnoticed.

We also need to have a test that covers the Isthmus transition block, see this comment.