Add a signal to allow for sniffing of when shortcut configurations change

This is needed for Gemini to be able to synchronise the shortcuts between
the two views. Possibly useful in other situations as well, but that's what
it's used for for now.

libs/main/KoMainWindow.cpp

@@ -1545,6 +1545,8 @@ void KoMainWindow::slotConfigureKeys()
         undoAction->setText(oldUndoText);
         redoAction->setText(oldRedoText);
     }
+
+    emit keyBindingsChanged();
 }
 
 void KoMainWindow::slotConfigureToolbars()

libs/main/KoMainWindow.h

@@ -188,6 +188,9 @@ signals:
     /// This signal is emitted when the color theme changes
     void themeChanged();
 
+    /// This signal is emitted when the shortcut key configuration has changed
+    void keyBindingsChanged();
+
 public slots:
 
     /**