tabBarController(_:sidebar:itemsForAddingTo:tab:)

Called when a new drag session is requesting items to add to the existing drag session in the sidebar from the specified tab. Return items if the specified tab can add to the drag session, or an empty array if nothing should be added.

optional func tabBarController(_ tabBarController: UITabBarController, sidebar: UITabBarController.Sidebar, itemsForAddingTo dragSession: any UIDragSession, tab: UITab) -> [UIDragItem]