Move object storage container_client to lib interface

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

Unit tests will be next step for those clients which should
be ok after miving to lib.

Partially implements blueprint consistent-service-method-names

Change-Id: I74c6d62058e0dcf9284f313c6f45d83c20597fc4
diff --git a/releasenotes/notes/make-account-client-as-stable-interface-d1b07c7e8f17bef6.yaml b/releasenotes/notes/make-account-client-as-stable-interface-d1b07c7e8f17bef6.yaml
index 9d5a1f5..5f899cf 100644
--- a/releasenotes/notes/make-account-client-as-stable-interface-d1b07c7e8f17bef6.yaml
+++ b/releasenotes/notes/make-account-client-as-stable-interface-d1b07c7e8f17bef6.yaml
@@ -7,3 +7,4 @@
     without any maintenance changes.
 
       * account_client
+      * container_client