podcast support (#203)

* implement search for shows/podcasts

* create Playable supertype for queue to contain tracks and episodes

* wip: implement playback of episodes

* load spotify id from uri instead of raw id to fix podcast playback

* show duration for podcast episodes

* implement generic status bar for playables (tracks and episodes)

omit saved indicator for now as the library does not yet support podcasts

* instead of only the last 50 fetch all episodes of a show

* refactor: extract Playable code to separate file

* implement playback/queuing of shows + sharing url

* implement podcast library

* migrate mpris code to Playable supertype

src/ui/library.rs

@@ -37,7 +37,12 @@ impl LibraryView {
             .tab(
                 "playlists",
                 "Playlists",
-                PlaylistsView::new(queue, library.clone()),
+                PlaylistsView::new(queue.clone(), library.clone()),
+            )
+            .tab(
+                "podcasts",
+                "Podcasts",
+                ListView::new(library.shows.clone(), queue, library.clone()),
             );
 
         Self { tabs }