This was first attempted in f64dc01bd1, but reverted, since I hadn't considered how to handle stripping state data from blocks.
This removes the abusable API RuntimeBlockStateRegistry::fromTypeId() and related methods. These were only used to allow ItemBlocks to magically start referencing other blocks if the blocks were overridden by a plugin, but this was never a well-supported use-case anyway.
Instead of relying on RuntimeBlockStateRegistry, we remember the state that the block had during its constructor, and use that to normalize the non-item properties for asItem().
closes#5609
This reverts commit f64dc01bd1.
I forgot that the ItemBlock constructor implicitly strips off any states
of the origin block, which is something that we unfortunately can't do
any other way right now, since the blocks don't remember their default
states.
