Using a help icon for confirmation dialogs is not recommended in the
latest UI guidelines for Mac, Linux and Windows.

References:
https://developer.apple.com/design/human-interface-guidelines/components/presentation/alerts/
https://developer.gnome.org/hig/patterns/feedback/dialogs.html
https://docs.microsoft.com/en-us/windows/apps/design/controls/dialogs-and-flyouts/dialogs

Currently the text is way to much on the left with this patch, therefore
this change depends on
https://github.com/eclipse-platform/eclipse.platform.ui/issues/116

For #149