Fixes EntityPotionEffectEvent
Fixes EntityPoseChangeEvent
Asynchronous chunk generation provides an opportunity for things
to happen async that previously fired synchronous-only events. This
patch is for mitigating those issues by various methods.
Also fixes correctly marking/clearing the entity generation flag.
This patch sets the generation flag anytime an entity is created
via StructureTemplate before loading from NBT to catch uses of
the flag during the loading logic. This patch clears the generation
flag from an entity when added to a ServerLevel for the situation
where generation happened directly to a ServerLevel and the
entity still has the flag set.