makeinstancesufo should not rely on lib copy=1 key

[frankrolf]

(Carrying over from a discussion on the RoboFont discord)

Using the current designspaceLib, it’s possible to use findDefault() to identify the default source.
https://fonttools.readthedocs.io/en/latest/designspaceLib/python.html#fontTools.designspaceLib.DesignSpaceDocument.findDefault

This implies that the XXX copy=1 keys are not necessarily set in modern .designspace files.
As a result, instance UFOs produced with makeinstancesufo may end up with scrambled glyph order.

I don’t see a scenario in which an instance built via makeinstancesUFO should not inherit the groups.plist/lib.plist from the default source UFO. I’d argue for these to always be transferred.