sorting-queue: move `draggable` setting
sorting-queue: move `draggable` setting

This commit moves the `itemsDraggable` setting in to the
`items` (sub-)map, as given by:

  items: {
    draggable: bool
  }

Also removed no longer used settings.

[breaking-change]

dossier/sortingdesk,dossier/sortingdesk,dossier/sortingdesk,dossier/sortingdesk,dossier/sortingdesk