Fatshark has a few weird string fields, where they provide a length
field, but then sometimes write a shorter, NUL-terminated string into
that same field and adding padding up to the "advertised" length.
To properly read those strings, we can't rely on just the length field
anymore, but need to check for a NUL, too.
Ideally, I would prefer the usual split per logging level, but that
seems to be somewhat complex with `tracing_subscriber`, so this simply
switches everything over to stderr, so that some of the experiment
commands can write results to stdout.
