Move object storage bulk_middleware_client to lib interface

object storage bulk_middleware_client is stable now and good to be moved
as stable library interface.

Partially implements blueprint consistent-service-method-names

Change-Id: I6b44fb9a692b947baadbe049b2f7d31e4ab51035
diff --git a/releasenotes/notes/migrate-object-storage-as-stable-interface-42014c7b43ecb254.yaml b/releasenotes/notes/migrate-object-storage-as-stable-interface-42014c7b43ecb254.yaml
new file mode 100644
index 0000000..d38f562
--- /dev/null
+++ b/releasenotes/notes/migrate-object-storage-as-stable-interface-42014c7b43ecb254.yaml
@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    Define object storage service clients as libraries
+    Add new service clients to the library interface so the other projects can use these modules as stable libraries without
+    any maintenance changes.
+
+      * bulk_middleware_client