Comment 1 for bug 1789015

There was previously code for Gtk::AccelMap::load to load the file and use that for menu keyboard shortcuts. This has long since been removed and presumably replaced with some other way of handling this: https://gitlab.com/inkscape/inkscape/commit/222304de408e85f01ace7b5ec9f965440ff1079e

It seems this was only ever used by Application::Editor, which was apparently part of a failed attempt to refactor Inkscape code around gtkmm. https://gitlab.com/inkscape/inkscape/commit/be8029ed57d68a7b8e94cfc5b82984a8b1c75e55

As such, I think this should be safe to remove.