Revamp Shared Memory Example: Change the used QSharedMemory constructor

Use QSharedMemory(const QNativeIpcKey &key) constructor to port away
from the deprecated QSharedMemory(const QString &) constructor.

Task-number: QTBUG-108858
Change-Id: I05615100f77f571fe32a3cf627c3df46baaa7f7a
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
(cherry picked from commit 976f30dc5939d887606cc4df33b80f6e9d3563ab)

examples/corelib/ipc/sharedmemory/dialog.cpp

@@ -5,6 +5,9 @@
 
 #include <QBuffer>
 #include <QFileDialog>
+#include <QNativeIpcKey>
+
+using namespace Qt::StringLiterals;
 
 /*!
   \class Dialog
@@ -30,8 +33,9 @@
   each button.
 */
 //! [0]
+
 Dialog::Dialog(QWidget *parent)
-  : QDialog(parent), sharedMemory("QSharedMemoryExample")
+    : QDialog(parent), sharedMemory(QNativeIpcKey(u"QSharedMemoryExample"_s))
 {
     ui.setupUi(this);
     connect(ui.loadFromFileButton, &QPushButton::clicked,