[WIP] [CR] Forest monster spawn group changes

A redo of old PR, with new functionalities. Basics were transferred, now I need and opinion/directions on these things:
1). Should giant insect chance of spawning grow as time goes on?
2). Should I pull in more giant insects into forest spawns, as it in my mind would make sense? Ex.: Giant centipedes, flies, mosquitoes?
3). Should I give zombie animal versions to other large animals, like zombears?.
4). If one is not completely aversed to this, what would be the best time frame for giant insect/zombie animal introduction, as it has great effect on game.