Draft: MacOS: raise ScriptFu dialogs to top when they are shown. Fix #12150

Draft: work in progress.

Intended to fix #12150 (closed)

In the current state, it solves that extension-script-fu's dialogs are behind other windows on second invocations, and solves that the dialog doesn't go away. But the problem that the Gimp window is not active when a plugin returns is not solved yet (the call to raise the window is not even called, so it is not in the correct place?)

Also not solved is the problem that extension-script-fu stays in the dock. Which I think is a packaging problem.