plugins: Fix getPropertiesFiles() for pluggable service plugins, CiscoNexusVSMEElement

Signed-off-by: Rohit Yadav <bhaisaab@apache.org>
api: Re-add deleted addProxyObject method on CloudException

- This was removed part of the response work
- Re-adding as this kind of method definition is available in several other
  exception classes and is used in a lot of cmd classes and in service layer
- TODO: We need to find a way to replace old code and refactor method with the
  new definition that gets only uuid.
- FIXME: Some tables don't have uuid for ex. ClusterVSMMapVO, in this case
  we should keep the method until we find a way to fix this issue

Partially reverting a88ce6bb7f495dddeb954d1fc7826176646b3590

Signed-off-by: Rohit Yadav <bhaisaab@apache.org>