pieces from available pieces disappear when places, and confirm button now puts the game into a playing state and hides placement state UI
Pawns now can have upgrades applied to them when purchased.
Changed shop to 3 items of each, added rarity tiers for items and upgrades. Shop is now kinda centered sometimes
Added gold display. Hides the board and pieces when shop is displayed.
Refactoring game.gd to split up move validation to individual pieces, added new scripts that inherit from Piece.gd
