Add EIP marker for better DevEx

We've added some very nice EIP-based logic in our codebase - things like `fork.is_eip_enabled(...)` and `pytest.mark.valid_from(EIP1234)`. It would be very nice if we could auto-add an EIP marker to tests that are marked valid from certain EIPs so we could fill tests for that EIP with something like:

```
uv run fill --clean --fork=Amsterdam -m EIP1234
```

This is a remaining thought from implementing EIP-7928 and having seen the EIP logic be merged into the code base. It made sense to add BAL expectations to older, more complex, tests in some cases. This would ideally make it so we can catch all the tests marked with the EIP7928 marker with a single `-m` command, for example, rather than looking for them and amassing some complex catch-all `-k` command.