Add in new endpoint with data for platform admin stats

Added in a new endpoint and DAO function to provide the data for the new
platform admin statistics page. The DAO method gets different data from
the Notifications / NotificationHistory table and also groups it differently.

The old endpoint has not been deleted yet to allow the numbers on the
old and new pages to be compared.

app/dao/services_dao.py

@@ -453,6 +453,34 @@ def fetch_aggregate_stats_by_date_range_for_all_services(start_date, end_date, i
     return query.all()
 
 
+@statsd(namespace='dao')
+def fetch_new_aggregate_stats_by_date_range_for_all_services(start_date, end_date):
+    start_date = get_london_midnight_in_utc(start_date)
+    end_date = get_london_midnight_in_utc(end_date + timedelta(days=1))
+    table = NotificationHistory
+
+    if start_date >= datetime.utcnow() - timedelta(days=7):
+        table = Notification
+
+    query = db.session.query(
+        table.notification_type,
+        table.status,
+        table.key_type,
+        func.count(table.id).label('count')
+    ).filter(
+        table.created_at >= start_date,
+        table.created_at < end_date
+    ).group_by(
+        table.notification_type,
+        table.key_type,
+        table.status
+    ).order_by(
+        table.notification_type,
+    )
+
+    return query.all()
+
+
 @transactional
 @version_class(Service)
 @version_class(ApiKey)