Backend: Use more specific methods for checking skull textures

[CalMWolfs]

What

• Using preprocessed methods
• Using more specific methods which means only checking one inventory slot of an armor stand for a skull texture instead of all five slots
  I converted a few of the existing uses of hasSkullTexture and the remaining ones are things i dont have unlocked for the most part (vamp slayer and crimson isle stuff)

Changelog Technical Details

• Slightly improved performance when checking armor stands for skull textures. - CalMWolfs