[CSStep] Rework how orphaned constraints are handled by splitter/component steps
Orphaned constraints can be re-introduced to the system by `setup`
of the component, and all of them could be returned back by
`SplitterStep::resume` there so no need to use destructor for that.
Also, orphan constraints have to be registered as regular constraints
by components as well as marked as "orphaned".
Committer
Davide Italiano