This adds a separate event before an entity is spawned by a spawner
which contains the location of the spawner too similarly to how the
SpawnerSpawnEvent gets called instead of the CreatureSpawnEvent for
spawners.
Adds an event to fire before an Entity is created, so that plugins that need to cancel
CreatureSpawnEvent can do so from this event instead.
Cancelling CreatureSpawnEvent rapidly causes a lot of garbage collection and CPU waste
as it's done after the Entity object has been fully created.
Mob Limiting plugins and blanket "ban this type of monster" plugins should use this event
instead and save a lot of server resources.
See: https://github.com/PaperMC/Paper/issues/917
