Allow extracting profiling information from pungi-gather.
`pungi-gather` (the tool that underlies both the `pkgset` and `gather`
phases) contains profiling code that will log statistics about how long
different function calls take. However, pungi-koji did not contain a
way to pass the ``--profiler`` argument to enable this.
This change adds a new configuration option ``gather_profiler`` which,
when set to true, simply passes the argument to `pungi-koji`. Hopefully
this can help shed some light on what is happening in some of our
Signed-off-by: Ralph Bean <email@example.com>