Both the instrument and utility functions were called `trace-cmd.py`.
`"-"`'s are not valid python identifiers therefore when trying to import
the `trace-cmd` module this causes an error.
- Add an option to the poller binary insert a marker into ftrace that
aligns with the first output entry. The option is exposed as an
instrument parameter.
- If this parameter is set, the resulting .csv will be post-processed to
update the timestamps to align with trace-cmd output.
- Change poller artifact names to use - instead of _ to be consistent
with trace-cmd artifact naming.
