Add/remove library on mobile devices

- Hide from main view; it is available in the context menu
- Prevents horizontal scrolling
- Also reinstate mobile context menu dividers for quicker legibility

src/js/views/Album.js

@@ -200,7 +200,7 @@ const Album = () => {
         >
           <I18n path="actions.play" />
         </Button>
-        {uriSource(uri) === 'spotify' && (
+        {uriSource(uri) === 'spotify' && !slim_mode && (
           <FollowButton
             uri={uri}
             is_following={album.in_library}

src/js/views/Artist/Artist.js

@@ -29,6 +29,7 @@ const Artist = () => {
   const { uri: encodedUri } = useParams();
   const uri = decodeUri(encodedUri);
 
+  const { slim_mode } = useSelector((state) => state.ui);
   const artistSelector = makeItemSelector(uri);
   const artist = useSelector(artistSelector);
   const albumSelector = makeItemSelector(artist?.albums_uris || []);
@@ -135,7 +136,7 @@ const Artist = () => {
                 >
                   <I18n path="actions.play" />
                 </Button>
-                {is_spotify && (
+                {is_spotify && !slim_mode && (
                   <FollowButton
                     uri={uri}
                     is_following={artist.in_library}

src/js/views/Playlist.js

@@ -30,6 +30,7 @@ const SORT_KEY = 'playlist_tracks';
 
 const Actions = ({
   encodedUri,
+  slim_mode,
   playlist: {
     uri,
     can_edit,
@@ -71,10 +72,12 @@ const Actions = ({
           >
             <I18n path="actions.play" />
           </Button>
-          <FollowButton
-            uri={uri}
-            is_following={in_library}
-          />
+          {!slim_mode && (
+            <FollowButton
+              uri={uri}
+              is_following={in_library}
+            />
+          )}
           <PinButton item={{ uri, name }} />
           <ContextMenuTrigger onTrigger={handleContextMenu} />
         </div>
@@ -298,6 +301,7 @@ const Playlist = ({
         playlist={playlist}
         onPlay={onPlay}
         handleContextMenu={handleContextMenu}
+        slim_mode={slim_mode}
       />
 
       <h4 className="no-bottom-margin">

src/scss/components/_context-menu.scss

@@ -320,10 +320,6 @@
 			}
 		}
 
-		&__divider {
-			display: none;
-		}
-
 		&__item {
 			font-size: 1.2rem;
 			font-weight: 800;