WiringTransform: fix non-determinism (#1799) (#1807)

* WiringUtils.sinksToSources: make sinkInsts order deterministic

* WiringUtils: make owners a LinkedHashMap

* Wiring: only make something a Wire if it isn't a port already

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
(cherry picked from commit c02c9b7f

)

Co-authored-by: Kevin Laeufer <kevin.laeufer@sifive.com>