Load blockstate json files from subfolders in assets/<id>/blockstates

This would be helpful for making resource packs more organised. For example, I could have a "wool" folder in "assets/minecraft/blockstates" for all 16 colours of wool.

This would be especially helpful as blockstates can't be renamed, so all wool/concrete/terracotta blockstate names start with the name of the colour. This makes finding related files difficult with most sorting methods.