Added skins

[IngoHHacks]

Adds experimental functionality for loading skins using texture sheet files. Still quite unfinished, but the most important issue is the skin rendering not working correctly. This version requires copying the APIAssets folder to BepInEx\plugins\APIAssets.

[xhayper]

Might be a better idea to rename from APIAssets to Assets and use whatever that embed resource is ( i am not sure that is ), if we can't use embed resource then we can keep the APIAssets

[IngoHHacks]

Should be fairly stable and usable now, except for the following issues:

• Icons and previews still incorrectly render default attachments This is due to SkeletonGraphics only being able to have a single Texture.
• The translucent layer during recruiting still messes with the render order
• Skins that no longer exist need to be reset from the save file More research needed. Just don't save any files with custom skins for now.