Let XP orbs pass through copper grates

Allow XP orbs to travel freely through copper grates. This would open up new possibilities for automated farms, especially those using trident killers on bedrock. Currently, we are able to collect item drops from within enclosed kill chambers (e.g. hoppers below mud blocks, hopper minecarts, etc.) without moving the drop in item form all the way to its final destination. XP drops, however, need to be physically transported to their destination. This presents a challenge: removing XP without allowing mobs to escape via the same route. This is simple for some farms, but quite difficult for others, such as cave spider farms. Allowing XP to move through copper grates would provide additional options for how to collect it