Updates required for Minecraft versions up to 1.21

[Nincodedo]

24W18A+

• Remove 1.21 feature flag
• Any fake enchanments should be migrated to datapack enchantments
• Loot table conditions for killer, direct_killer, and killer_player are now attacker, direct_attacker, and attacking_player
• Predicate enchantment is now enchantments with a very different layout
• New predicates that will be useful: is_on_ground and is_flying

24W19A+

• Tag directories have been renamed

24W21A+

• Tag directories have been renamed

1.21+

• Replace @e[sort=nearest,limit=1] with @n
• Structures should use liquid_settings ignore_waterlogging to not be flooded all the time