[BREAKING] Item Usage Overhaul

-De-hardcode elemental orb values
-De-hardcode exp items
-Change ShopChest format (temporary, drop system overhaul will replace it entirely)
-Food healing actually uses Ability data for real HP amounts

src/main/java/emu/grasscutter/game/props/ItemUseAction/ItemUseSelectItems.java

@@ -0,0 +1,38 @@
+package emu.grasscutter.game.props.ItemUseAction;
+
+import emu.grasscutter.data.GameData;
+import emu.grasscutter.game.inventory.GameItem;
+import emu.grasscutter.game.props.ActionReason;
+
+public abstract class ItemUseSelectItems extends ItemUseAction {
+    protected static final int INVALID = -1;
+    protected int[] optionItemIds;
+
+    protected int getItemId(int index) {
+        if ((optionItemIds == null) || (index < 0) || (index > optionItemIds.length)) return INVALID;
+        return this.optionItemIds[index];
+    }
+
+    protected int getItemCount(int index) {
+        return 1;
+    }
+
+    protected GameItem getItemStack(int index, int useCount) {
+        int id = this.getItemId(index);
+        int count = this.getItemCount(index);
+        if (id == INVALID || count == INVALID) return null;
+
+        var item = GameData.getItemDataMap().get(id);
+        if (item == null) return null;
+
+        return new GameItem(item, count * useCount);
+    }
+
+    @Override
+    public boolean useItem(UseItemParams params) {
+        var itemStack = this.getItemStack(params.optionId - 1, params.count);
+        if (itemStack == null) return false;
+
+        return params.player.getInventory().addItem(itemStack, ActionReason.Shop);
+    }
+}