Making predicate "location_check" also support the new item check

The snapshot 24w10a just added a way of checking entity and block inventories. Even though this works on entities with predicates, it does not work on blocks. The new "slots" sub-predicate cannot be used on blocks. I hope this feature gets added. It would be great on checking containers for specific items. It could be added to the "location_check" condition.

( I am aware that execute command can check container items. However, I aim to combine many conditions in one predicate file so it is clear in file and easier to use. )