FR: Auto-culling for alpha-blended particles that slow down FPS

If the player is next to a ship that is emitting damage spew, and the radii for that ship's damage spew is on the bigger side (> 2.0 meters), there are considerable FSP drops. Video is attached, with FPS drop (60 to mid 30's).

In talking with @EatThePath, the idea arose of making any alpha-blended particles spawn less often or die faster if the framerate is low, or making them subject to a performance setting. Given the recent optimizations to FSO, it might be very useful to investigate of discuss this possible optimization as well.

https://user-images.githubusercontent.com/14077810/190884620-6c7e0508-4294-40a9-ae79-eab47ecb5d13.mp4