Support instantiation of same model vnfs/vf-modules

Support instantiation of same model vnfs/vf-modules

When instantiating a service with multiple vnfs and/or vfmodules
SO would differentiate using ModelCustomizationId. This would cause
issues when creating multiple instances of same model resource, and
each lookup would return the same object.

Instead of using ModelCustomizationId, this patch enables SO to use
instanceName parameter to differentiate the resources. Validation was
added to ensure that instanceNames are provided if there are multiple
resources of the same model. If there are no duplicate resources and
instanceName is not set, SO will default to previous logic using
ModelCustomizationId.

In order to properly associate vfmodules with their parent vnfs, the
Resource class was augmented with a parent reference which maintains
the relationship in further processing.

Id generation logic was corrected to ensure that multiple resources
of the same model are assigned unique instance ids and references to
parent instanceId.

Issue-ID: SO-3677
Change-Id: If39a0138f501177e12262f8e911137012e287fca
Signed-off-by: Michael Pruss <michael.pruss@bell.ca>