Add check when equipping items to animals for 1.21+

[CatTeaA]

Check permissions when players equip Carpet, Harness, Horse_Armor, Nautilus_Armor or Saddle to animals
(sometimes, players do not want others to modify the equipment of animals within their own residence)

Small Change:

1. isEmpty() check does not work in Spigot, so use AIR instead to check for empty slots.
2. add "parrot_poisonous_food" to prevent players from poisoning parrots.