Add generic session persistence api

Some actions are common to all types of session persistence profiles,
so this patch adds a generic resource for those actions.
In addition the list action should return only resources of the
requested type.

Change-Id: I803bb4ad9ed031c44b06d7eb99f00fa5491d3869

vmware_nsxlib/v3/exceptions.py

@@ -55,6 +55,10 @@ class ObjectAlreadyExists(NsxLibException):
     message = _("%(object_type)s already exists")
 
 
+class NotImplemented(NsxLibException):
+    message = _("%(operation)s is not supported")
+
+
 class ObjectNotGenerated(NsxLibException):
     message = _("%(object_type)s was not generated")