the 'uris' is passed from page/PagePlaylist.vue to handle a dynamic 'random'
smartpl playlist - we cannot add via 'playlist.uri' because when it will ask
the server for that uri it will generate another set of tracks, different to
the ones on display of the playlist page
This will allow to open a dialog outside of the ListItem component. Also
reduces the size of the generated DOM tree by only including one dialog
per page (per object type) and not for each list item.
