Make the unpack button idempotent on action history

[sharmaeklavya2]

If you press the 'unpack' button, items would be unpacked from the bins and arranged back in the inventory. This also appends an action to the action history, so that you can use undo/redo buttons.

However, we don't want to append 'unpack' to history when the bins are already empty. This will also signal the users that pressing the button didn't cause anything.

We can maybe also disable the unpack button if the bins are already empty and the items are already well-arranged in the inventory.