conf: Rework/rename virDomainObjListFindByIDRef
    
    Rework the code such that virDomainObjListFindByID will always
    return a locked/ref counted object so that the callers can
    always do the same cleanup logic to call virDomainObjEndAPI.
    Makes accessing the objects much more consistent.
    
    NB:
    There were 2 callers (lxcDomainLookupByID and qemuDomainLookupByID)
    that were already using the ByID name, but not virDomainObjEndAPI -
    these were changed as well in this update/patch.
    
    Signed-off-by: John Ferlan <jferlan@redhat.com>
    Reviewed-by: Jim Fehlig <jfehlig@suse.com>