ADDED: Option to assign unique reference designators to footprints
created with the array tool [pcbnew]
CHANGED: Array creator dialog no longer displays pad numbering properties
when in the board editor. [pcbnew]
Fixes https://gitlab.com/kicad/code/kicad/-/issues/2354
The CONFIG_SAVE_RESTORE_WINDOW class does not need to be tied
to the array dialog, put it in common/widgets.
Also do a refactor and tidy-up of the the class, use a union for (slightly)
better type-safety and syntax (a variant would be better but that's C++17).
Also enable integral field save/restore from text boxes.