get Block Texture Properties
Returns a map of custom block state properties to be used for the block texture item. These properties will be merged with the vanilla block state properties of the block.
Your map should be in the form of propertyName -> (propertyValue, numberOfPossibleValues). For example, if you have a property called "facing" that can be "up", "down", "north", "south", "east", or "west", you may return mapOf("facing" to ("north", 6)).
When overriding this method you most likely want to work off the result of super.getBlockTextureProperties() instead of returning a new map entirely, to ensure that any properties provided by superclasses are preserved. (e.g. RebarDirectionalBlock)