ChallengeUtil

Add a containerBlocks set and initialization to BlockBreakRandomizerListener to exclude container/storage blocks from drop randomization so their contents are preserved. initializeContainerBlocks() registers chests, trapped/ender chests, all shulker box colors, barrel, furnace variants, smoker, blast furnace, dispenser, dropper, hopper, brewing stand, etc., and is invoked from the constructor. The block-break handler now returns early for container blocks.