The only parts of the old weapon data that worked well (didn't commonly
result in empty pylons) did this implicitly, so make the grouping
explicit.
This also moves the data out of Python and into the resources, which
both makes the data moddable and isolates us from a huge amount of
effort and a save compat break whenever ED changes weapon names.
I didn't auto migrate the old data since the old groups were not
explict and there's no way to infer the grouping. Besides, since most of
the weapons were *not* grouped, the old data did more harm than good in
my experience. I've handled the AIM-120 and AIM-7 for now, but will get
at least all the fox 3 missiles before we ship.
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