this is a more tame version of my initial attempt to firehose item NBT. It marginalizes the use of item NBT to the places where it's needed on interfaces, leaving the internals clean to operate on whatever they like.
the intentions of this are good, but the usability is terrible and it's not fit for purpose. Since there are a total of zero plugins on Poggit which use this garbage, it makes more sense to eliminate the technical debt. See #2766 for discussion about replacing this.
the reasoning for this is that the world version number should have accounted for a chunk format change. If it didn't, then we assume any chunk with a wrong version number is corrupted, since the handling of unknown formats is the same as that of corrupted chunks.
There are a few motivations here:
1) Less boilerplate code (this can be written inline)
2) It's possible to provide multiple constructors for different packet variations to reduce the chance of errors.
3) It makes things catch fire on updates in ways that static analysers can understand.
It's not guaranteed that objects provided are the same as those in the enum registry, so they can't be directly compared.
Implementing comparison with === would require some kind of __equals() implementation or an extension to hook into such functionality.
This has been a pain point for a long time due to the misleading nature of the name "level". It's also confusing when trying to do things like getting the XP level of the player or such, and also does not translate well to other languages.
This transition was already executed on the UI some time ago (language strings) and now it's time for the same change to occur on the API.
This will burn a lot of plugins, but they'll acclimatize. Despite the scary size of this PR, there isn't actually so many changes to make. Most of this came from renaming `Position->getLevel()` to `Position->getWorld()`, or cosmetic changes like changing variable names or doc comments.
