LSP: implement call hierarchy

Fixes: QTCREATORBUG-11660
Change-Id: I006872ba598a807f1f9f16d134fe9ce4fe5dd09d
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/languageclient/callhierarchy.h

@@ -0,0 +1,20 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0 WITH Qt-GPL-exception-1.0
+
+#include <coreplugin/inavigationwidgetfactory.h>
+
+#pragma once
+
+namespace LanguageClient {
+
+class CallHierarchyFactory : public Core::INavigationWidgetFactory
+{
+    Q_OBJECT
+
+public:
+    CallHierarchyFactory();
+
+    Core::NavigationView createWidget()  override;
+};
+
+} // namespace LanguageClient