Allow stockpile to be configured to accept local parts only

I’m making my own door panels at the moment, but quite a long way away from the stockpile. Unfortunately every time the stockpile needs refilling, it’s preferencing the import point instead of my own product. Furthermore, even if I then set the door manufacture station to take local products only, it considers the stockpile to be “local”.

Indeed, I need to fix this, and plan to do so…