Meson: Flatten directory hierarchy

Keep tests/ and icons/ but put the rest into the toplevel.

The previous setup was so different from the rest of the bunch that
it regularly stuck out in maintenance tasks.

Change-Id: I69821be6268f69682353a388f6bb1fa343215303
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/mesonprojectmanager/projecttree.h

@@ -0,0 +1,24 @@
+// Copyright (C) 2020 Alexis Jeandet.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0+ OR GPL-3.0 WITH Qt-GPL-exception-1.0
+
+#pragma once
+
+#include "mesoninfoparser.h"
+#include "mesonprojectnodes.h"
+
+#include <utils/fileutils.h>
+
+namespace MesonProjectManager {
+namespace Internal {
+
+class ProjectTree
+{
+public:
+    ProjectTree();
+    static std::unique_ptr<MesonProjectNode> buildTree(const Utils::FilePath &srcDir,
+                                                       const TargetsList &targets,
+                                                       const std::vector<Utils::FilePath> &bsFiles);
+};
+
+} // namespace Internal
+} // namespace MesonProjectManager