PRIMARY_GDSII_STREAMOUT_TOOL behavior/doc

[smunaut]

Description

So when reading PRIMARY_GDSII_STREAMOUT_TOOL I actually only expected it to change the default flow behavior. But that if I had my own custom flow steps and only had one of the StreamOut that it would use that one for the GDS.

Proposal

In the copy step, I would copy if either the file doesn't exist or if the primary tool is set to that step (potentially overwriting the previous one made by non-primary tool).