cmd/evm: output stateroot in statetest result

[holiman]

Hi,
See ethereum/go-ethereum#26297 -- I was wondering if you could cherry-pick this into erigon aswell?

For one thing, it makes it possible to run (without tracing) yet obtain the stateroot, regardless of whether the test passes or not. Currently, it is only possible if the test fails, and then a bit of parsing is needed to pick it out from an error mesage .