fixes#5858
technically speaking, the sideways states for non-fully-grown stems shouldn't exist, but they do in Bedrock, and changing this code to split non-fully-grown stems from fully grown ones would likely require BC breaks.
This was the minimum necessary to achieve the desired functionality.
this coincidentally fixes mangrove doors being tagged with unwanted blockstate runtime IDs. Their items client-side are not actually blockitems, so the client doesn't expect them to have blockstate IDs attached.
This reduces the chaos in the creative inventory slightly (for some reason the client responds to this stuff by putting random creative items in the wrong places), but the mess is still substantial and I don't know what caused the rest of it.
closes#5818
technically we shouldn't be breaking BC of internals signatures in a patch release, but it's internals, and that's an unwritten rule anyway. In any case, no one is likely to be affected.
these started to get flattened in 1.19, and rather than dump them in random places in the main function I made a new method, creating placement inconsistencies.
this information will allow us to correct for any bugs introduced by past versions.
however, we still need to propagate this information to permit actually using it when loading data.
to be consistent, these shouldn't be exposed in the API like this...
I'm not very happy with the whole 'type ID map' paradigm (particularly its lack of static analysis guarantees), but the most important thing right now is to get this stuff out of the API so that plugin devs don't try and abuse it. We're not going to change the whole system days before PM5 release.
At the time when I wrote this code, I was still in the head space of the kind of ID hijacking that PM4 plugins do to override built-in blocks.
However, this kind of internal ID reuse makes no sense in PM5, since said IDs are only used in the core itself at runtime to identify types and states.
Even if we were to allow overriding block deserializers, overriding serializers makes no sense whatsoever, since the original block would continue to exist and be accessible.
There is a case to be made to allow overriding the deserializer, but not for the serializer.
right now, I don't see an obvious reason to do this. If it turns out I was wrong later on, we can add functionality back, but we can't remove functionality after release.
this significantly reduces the size of schemas when state remaps are used (see pmmp/BedrockBlockUpgradeSchema@85b83b360e).
in addition, this will likely offer a substantial performance and memory saving when walls get flattened, which will eventually happen.
