Add EntityAvoidEntityEvent

[joshuaprince]

Add a new event for when an entity avoids another entity.

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This is a replacement for #10798. The original intent was to fire an event when an armadillo rolls up, but this covers even more entities to be as generic as possible.

Affected Entities

I tested with these entities (all entities that have an AvoidEntityGoal, plus extra handling for armadillos and villagers). Cancelling the event behaves as expected, and in some cases, ends violently.

• Fish -> Player
• Dolphin -> Guardian
• Fox -> Player, Wolf, Polar Bear
• Skeleton -> Wolf
• Creeper -> Ocelot, Cat
• Evoker -> Player
• Spider -> Armadillo
• Wandering Trader -> Zombie and Illager variants
• Ocelot, Cat -> Player
• Panda -> Player
• Rabbit -> Player
• Wolf -> Llama
• Armadillo -> Player, Undead
• Villager -> Zombie and Illager variants

(should this be documented somewhere?)