I misinterpreted some code as a risk of entity loss, but now
after deeper study, I see how that code was used more and why
it was adding entities to chunks that they shouldn't have been
in during a world transfer process.
Vanilla logic here would allow us to remvoe an entity from
its current chunk, and if it was going to move into an unloaded
chunk, that entity would not be added to the unloaded chunk.
This is bad because this will result in the entity being lost!
In almost all cases, the chunk will be loaded, but in the event
it wasn't, instead of losing the entity, load the chunk to add
the entity to it.
This enables us a fast reference to the entities current chunk instead
of having to look it up by hashmap lookups.
We also store counts by type to further enable other performance optimizations in later patches.
