QmlDesigner: Add support for .ktx

Task-number: QDS-5849
Change-Id: Ibe0bb3f2480a25a2d80793526d6581e89c22529f
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Henning Gründl <henning.gruendl@qt.io>

src/plugins/qmlprojectmanager/fileformat/filefilteritems.cpp

@@ -300,6 +300,7 @@ ImageFileFilterItem::ImageFileFilterItem(QObject *parent)
     // supported image formats according to
     QList<QByteArray> extensions = QImageReader::supportedImageFormats();
     extensions.append("hdr");
+    extensions.append("ktx");
     for (const QByteArray &extension : qAsConst(extensions))
         filter.append(QString::fromLatin1("*.%1;").arg(QString::fromLatin1(extension)));
     setFilter(filter);