feat(api): Add NodeInfo 2.1

Part-of: <https://dev.funkwhale.audio/funkwhale/funkwhale/-/merge_requests/2604>

api/funkwhale_api/instance/stats.py

@@ -1,6 +1,6 @@
 import datetime
 
-from django.db.models import Sum
+from django.db.models import Count, F, Sum
 from django.utils import timezone
 
 from funkwhale_api.favorites.models import TrackFavorite
@@ -22,6 +22,39 @@ def get():
     }
 
 
+def get_content():
+    return {
+        "local": {
+            "artists": get_artists(),
+            "releases": get_albums(),
+            "recordings": get_tracks(),
+            "hoursOfContent": get_music_duration(),
+        },
+        "topMusicCategories": get_top_music_categories(),
+        "topPodcastCategories": get_top_podcast_categories(),
+    }
+
+
+def get_top_music_categories():
+    return (
+        models.Track.objects.filter(artist__content_category="music")
+        .exclude(tagged_items__tag_id=None)
+        .values(name=F("tagged_items__tag__name"))
+        .annotate(count=Count("name"))
+        .order_by("-count")[:3]
+    )
+
+
+def get_top_podcast_categories():
+    return (
+        models.Track.objects.filter(artist__content_category="podcast")
+        .exclude(tagged_items__tag_id=None)
+        .values(name=F("tagged_items__tag__name"))
+        .annotate(count=Count("name"))
+        .order_by("-count")[:3]
+    )
+
+
 def get_users():
     qs = User.objects.filter(is_active=True)
     now = timezone.now()