add subplugin field support and new Cloud Artifact class

. add subplugin field to integrate with Distribution framework
. add new Cloud Artifact which is to be used by subplugin like k8s
. update test .json file to include reception and forward fields
. add dummy test class to ensure the flow works as expected
. fix typos

Change-Id: I9d69d88e448a18247e19b3b7a6062b20814b5f8c
Issue-ID: MULTICLOUD-512
Signed-off-by: liboNet <libo.zhu@intel.com>
27 files changed