Block a user
Add containers/pods needed for running system tests.
The stack will also need the cerc/plugeth and cerc/plugeth-statediff - but, that would make it almost the same as fixturenet-plugeth-loaded. So maybe we should keep this one as a basic non-statediff stack?
Add --pluginsdir flag.
Looks good but would be a bit cleaner to use the same pattern as DataDirFlag to set the default