[gi-overrides] Add event methods to all event union members
[gi-overrides] Add event methods to all event union members

https://bugzilla.gnome.org/show_bug.cgi?id=642554

alexef/pygobject,alexef/pygobject,pexip/pygobject,jdahlin/pygobject,thiblahute/pygobject,davidmalcolm/pygobject,davibe/pygobject,jdahlin/pygobject,GNOME/pygobject,davibe/pygobject,MathieuDuponchelle/pygobject,sfeltman/pygobject,thiblahute/pygobject,davibe/pygobject,GNOME/pygobject,choeger/pygobject-cmake,jdahlin/pygobject,thiblahute/pygobject,davibe/pygobject,choeger/pygobject-cmake,MathieuDuponchelle/pygobject,sfeltman/pygobject,sfeltman/pygobject,nzjrs/pygobject,davidmalcolm/pygobject,MathieuDuponchelle/pygobject,nzjrs/pygobject,pexip/pygobject,pexip/pygobject,choeger/pygobject-cmake,GNOME/pygobject,alexef/pygobject,davidmalcolm/pygobject,nzjrs/pygobject