Fixes https://github.com/Khopa/dcs_liberation/issues/417, though the
notes on that bug about this being non-optimal for skynet are still
true. This doesn't make skynet behavior any worse though, and does
improve it some compared to not having PD.
Adds two new SA-10 generator variants:
* Tier 2, with SA-15 for point defense
* Tier 3, with SA-15 for point defense and the Shilka upgraded to a
Tunguska.
Updated factions that are capable of those systems, added missing SAMs
to those factions, and removed use of SA-19 as an independent SAM from
those factions. Will do a larger audit of faction SAMs later.
