Add item slot to the "/item" command that refers to the first free slot

The "/item" command is a fantastic edition to 1.17, but I feel it's missing one super obvious addition.

When picking up items, those items go into the first free slot in the inventory (going from "container.0" to "container.35")

The /give command also does this by summoning an item that is instantly picked up by the player.

It seems like it wouldn't be too hard to copy the code that determines what slot a picked up item goes into and use it to determine the first free slot

There is virtually no way to do this right now, for example let's say you wanted to copy the item that player A is holding and give it to player B, since "/give" and "/summon" have to have a specific item as their input, you can't use those to get an item from a container, meaning it's practically impossible.

This would massively benefit datapack creators like myself as currently this restriction turns up more than first expected.