Turn AnthroSystem into an ECS component of its own

[vulppine]

Description

Currently, AnthroSystem's Markings/Species body changes piggyback off of the existing HumanoidAppearance component, mostly to try and avoid the issue of dealing with the amount of code changes that would be required.

However, to make it more modular (and express the power of object composition), it would be nicer to move the marking system, and anything that manages the species-related stuff to its own component.

This should be done to avoid messing with merges if possible - especially since AnthroSystem touches a good chunk of base SS14 UI code (especially in the character setup screen) in order to implement the marking system.