[feat][backend] trace ingestion idl (#465)

* add idl

Author: cuichen01

idl/thrift/coze/loop/observability/coze.loop.observability.ingestion.thrift

@@ -0,0 +1,7 @@
+namespace go coze.loop.observability.ingestion
+
+include "../../../base.thrift"
+
+service IngestionService {
+
+}