Move volume v2 service clients to v3 dir

Moving all existing volume v2 service clients to
v3 dir. These service clients will be available as
v3 service clients.

For backward compatibility, keeping all service
clients importable from volume.v2 dir with deprecation
warning.

This patch is starting patch to make volume service clients
cleanup for v3 API testing as default.

Change-Id: I5888740f94d9f1ef8ce3fac78e4ce76ae650a6fd
diff --git a/releasenotes/notes/volume-v3-service-clients-a863a6336af56cca.yaml b/releasenotes/notes/volume-v3-service-clients-a863a6336af56cca.yaml
new file mode 100644
index 0000000..b572a34
--- /dev/null
+++ b/releasenotes/notes/volume-v3-service-clients-a863a6336af56cca.yaml
@@ -0,0 +1,12 @@
+---
+features:
+  - |
+    Adds volume service clients for v3 APIs. As v3 base API should be
+    identical to v2 APIs, we just copy all existing v2 service client
+    for v3 API.
+deprecations:
+  - |
+    Deprecates the volume service clients for v2 APIs. Volume v2 APIs
+    are deprecated in all supported stable branches, so it's time
+    to deprecate the tempest service clients for v2 APIs and remove in future
+    release.