QWidget::addAction not adding all standard key shortcuts

We have a bunch of convenience functions for adding actions to widgets/menus/toolbars. Some of them take a QKeySequence as a way to produce a shortcut for the action. Which allows you to pass a `QKeySequence::StandardKey` due to the implicit constructor. The issue is that the implicit constructor will only pick the first shortcut, not all the possible standard shortcuts. We should probably add overloads to QWidget and friends that take a QKeySequence::StandardKey, so that we can call addShortcut*s* on the resulting action.