Improve context menus to make the UX/UI more consistent (#923)

* Add save option to context menu of all possible ListItems

* Add play options to context menus

* Fix for playlists and tracks

* Move playback controls into main menu

src/model/show.rs

@@ -150,6 +150,16 @@ impl ListItem for Show {
         Some(format!("https://open.spotify.com/show/{}", self.id))
     }
 
+    #[inline]
+    fn is_saved(&self, library: Arc<Library>) -> Option<bool> {
+        Some(library.is_saved_show(self))
+    }
+
+    #[inline]
+    fn is_playable(&self) -> bool {
+        true
+    }
+
     fn as_listitem(&self) -> Box<dyn ListItem> {
         Box::new(self.clone())
     }