Reimplement GUIs for Python plug-ins missing them
As @NikcCDC notes in #8035 (closed), some Python plug-ins have no GUI. This was because back then, I hadn't implemented yet our new dialog generation API and didn't want to play around with GTK code, knowing it would soon be much faster and easier to create dialogs for our plug-ins.
So this report is just a small reminder that we must check if all Python plug-ins which used to have a GUI still have one in the 3.0. If not we must add one.