Minor update to add the groundwork for a shield-related features.

Additions

• Added new class for easily executing callbacks from an item.
• Added new interface, BlockingItem.
  • Items with the ability to block attacks should implement this interface.
  • It contains methods that allow the item to configure the nature of its blocking.
    • Cooldown duration when disabled.
    • How many ticks the item must be used for until it is actively blocking attacks.
    • Callbacks
      • Damaging the shield.
      • Post-block actions.
• Added enchantment callback for post-block actions.
• Added enchantment context (for conditions) for post-block actions.
  • In this context, the target is the owner of the enchanted item, the one who blocked the attack.
• Added debug shield item and debug blocking enchantment for developers.
• [LilyLib] Enchantment descriptions now also generate a .description key as well as the existing .desc key.