Add `UnpackedLootTableHolder` support for Lootr Chests

[BlayTheNinth]

Lootr replaces chests with its own block entity, so it's currently unaffected by UnpackedLootTableHolder.

[BlayTheNinth]

UnpackedLootTableHolder isn't a great solution, and I don't like the idea of having to do this at the block entity / entity level for everything. It turns out NeoForge already has a solution for this problem via LootContext#queriedLootTableId, so Balm should use that (and create an equivalent for Fabric) instead. #240