QmlDesigner: Add source path watcher

The watcher is only watching directories and then searches for file
stat changes. It is compressing signals too. So if files are changes
in a very short time frame they are compressed to one change.

Task-number: QDS-4776
Change-Id: I90052a0d5dba01467b505070fb58b04ea5576294
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

tests/unit/unittest/projectstoragepathwatchermock.h

@@ -0,0 +1,41 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#pragma once
+
+#include "googletest.h"
+
+#include "projectstorage/projectstoragepathwatcherinterface.h"
+
+class MockProjectStoragePathWatcher : public QmlDesigner::ProjectStoragePathWatcherInterface
+{
+public:
+    MOCK_METHOD(void, updateIdPaths, (const std::vector<QmlDesigner::IdPaths> &idPaths), ());
+    MOCK_METHOD(void, removeIds, (const QmlDesigner::ProjectPartIds &ids), ());
+    MOCK_METHOD(void,
+                setNotifier,
+                (QmlDesigner::ProjectStoragePathWatcherNotifierInterface * notifier),
+                ());
+};