Adds ChessPiece's species hardsuit sprites

Adds ChessPiece's onmob and inventory sprites for unathi and skrell hardsuits, as well as nicer tajaran hardsuit inventory sprites to replace the current placeholder ones. Adds hardsuit spritesheet entries for unathi (skrell will come later).
Merge pull request #6177 from mwerezak/species-suits

Adds ChessPiece's species hardsuit sprites