[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/ItemUseAddServerBuff.java

@@ -0,0 +1,24 @@
+package emu.grasscutter.game.props.ItemUseAction;
+
+import emu.grasscutter.game.props.ItemUseOp;
+
+public class ItemUseAddServerBuff extends ItemUseInt {
+    private int duration = 0;
+
+    @Override
+    public ItemUseOp getItemUseOp() {
+        return ItemUseOp.ITEM_USE_ADD_SERVER_BUFF;
+    }
+
+    public ItemUseAddServerBuff(String[] useParam) {
+        super(useParam);
+        try {
+            this.duration = Integer.parseInt(useParam[1]);
+        } catch (NumberFormatException ignored) {}
+    }
+
+    @Override
+    public boolean useItem(UseItemParams params) {
+        return params.player.getBuffManager().addBuff(this.i, this.duration, params.targetAvatar);
+    }
+}