Fix memory leak in Qt Quick Controls icon

The implementation of the icon property uses the internal
QThemeIconInfo struct from qtbase. That is low level and expects the
user to handle memory deallocation, and this was missing.

Fixes: QTBUG-93050
Pick-to: 6.2
Change-Id: Ied6488aa8871c246d3781a3db47f40130dc19bcc
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

src/quickcontrols2impl/qquickiconimage.cpp

@@ -42,6 +42,12 @@
 
 QT_BEGIN_NAMESPACE
 
+QQuickIconImagePrivate::~QQuickIconImagePrivate()
+{
+    qDeleteAll(icon.entries);
+    icon.entries.clear();
+}
+
 bool QQuickIconImagePrivate::updateDevicePixelRatio(qreal targetDevicePixelRatio)
 {
     if (isThemeIcon) {
@@ -132,6 +138,7 @@ void QQuickIconImage::setName(const QString &name)
     if (d->icon.iconName == name)
         return;
 
+    qDeleteAll(d->icon.entries);
     d->icon = QIconLoader::instance()->loadIcon(name);
     if (isComponentComplete())
         d->updateIcon();

src/quickcontrols2impl/qquickiconimage_p_p.h

@@ -59,6 +59,7 @@ class Q_QUICKCONTROLS2_PRIVATE_EXPORT QQuickIconImagePrivate : public QQuickImag
     Q_DECLARE_PUBLIC(QQuickIconImage)
 
 public:
+    ~QQuickIconImagePrivate() override;
     void updateIcon();
     void updateFillMode();
     qreal calculateDevicePixelRatio() const;