[sorting] Add Added option to root sort for albums

src/js/locale/en.yaml

@@ -90,6 +90,7 @@ fields:
     followers: Followers
     popularity: Popularity
     date: Date
+    added: Added
 time:
   seconds:
     short: secs

src/js/views/Library/Albums.js

@@ -199,6 +199,10 @@ class Albums extends React.Component {
         value: 'release_date',
         label: i18n('fields.filters.date'),
       },
+      {
+        value: 'added_at',
+        label: i18n('fields.filters.added'),
+      },
       {
         value: 'tracks',
         label: i18n('fields.filters.tracks'),