QMenu: Accept accelerators typed on keypad

Add Qt::KeypadModifier (and the combination with Qt::AltModifier) to the
modifiers that may be set in a key event in order to trigger a menu
action via its accelerator.

Otherwise, an action that has a number set as the accelerator (e.g.
using text "&1 Exit"), cannot be triggered by typing the corresponding
number on the keypad.

Fixes: QTBUG-73390
Pick-to: 6.8
Change-Id: I0fa63b0c5f23823c61e159fcc72f7245215f8aae
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
(cherry picked from commit ca4334b)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/widgets/widgets/qmenu.cpp

@@ -3363,8 +3363,11 @@ void QMenu::keyPressEvent(QKeyEvent *e)
     }
 
     if (!key_consumed) {                                // send to menu bar
-        if ((!e->modifiers() || e->modifiers() == Qt::AltModifier || e->modifiers() == Qt::ShiftModifier) &&
-           e->text().size()==1) {
+        const Qt::KeyboardModifiers modifiers = e->modifiers();
+        if ((!modifiers || modifiers == Qt::AltModifier || modifiers == Qt::ShiftModifier
+             || modifiers == Qt::KeypadModifier
+             || modifiers == (Qt::KeypadModifier | Qt::AltModifier))
+            && e->text().size() == 1) {
             bool activateAction = false;
             QAction *nextAction = nullptr;
             if (style()->styleHint(QStyle::SH_Menu_KeyboardSearch, nullptr, this) && !e->modifiers()) {