Build rest endpoint to read service stats

- get stats by service id
- returns a list of stats objects

Not paginated - have 1 row per day.

app/notifications_statistics/rest.py

@@ -0,0 +1,25 @@
+from flask import (
+    Blueprint,
+    jsonify,
+)
+
+from app.dao.notifications_dao import (
+    dao_get_notification_statistics_for_service
+)
+from app.schemas import notifications_statistics_schema
+
+notifications_statistics = Blueprint(
+    'notifications-statistics',
+    __name__, url_prefix='/service/<service_id>/notifications-statistics'
+)
+
+from app.errors import register_errors
+
+register_errors(notifications_statistics)
+
+
+@notifications_statistics.route('', methods=['GET'])
+def get_all_templates_for_service(service_id):
+    templates = dao_get_notification_statistics_for_service(service_id=service_id)
+    data, errors = notifications_statistics_schema.dump(templates, many=True)
+    return jsonify(data=data)