[Libvirt-cim] [PATCH 0 of 3] Reference SBLIM host system when possible

This patch set (eventually) makes the providers return references to the SBLIM Linux_ComputerSystem instance, if that provider is available. This makes all of the Hosted* associations (and others) correctly point to the SBLIM provider when possible. As a fallback, we continue to return our fake instances if the SBLIM provider isn't installed.