[DinoMod] predator nest improvements

[LyleSY]

Summary

Mods "[DinoMod] predator nest improvements"

Purpose of change

Make predator nests more interesting and diverse

Describe the solution

New abandoned predator nest
adds human skull to mainline remains_human_generic item group
Add a chance to get human and animal corpses, as well as people parts to all predator nests

Describe alternatives you've considered

Create complicated new nested nest mapgen for each class of dino with linked variants. Not sure that would be better but it would be impressive.

Testing

Game loads no errors, new map spawns and looks right

Additional context

N/A