Remove #include <utils/fileutils.h> from most header files

It has some platform specific warts, filepath.h is somewhat
cheaper and less ugly overall.

Partially clean up surroundings

Change-Id: Ida1fd470ec020f69c446109427f92a08e879789f
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/mesonprojectmanager/projecttree.h

@@ -0,0 +1,22 @@
+// Copyright (C) 2020 Alexis Jeandet.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#pragma once
+
+#include "mesoninfoparser.h"
+#include "mesonprojectnodes.h"
+
+#include <utils/filepath.h>
+
+namespace MesonProjectManager::Internal {
+
+class ProjectTree
+{
+public:
+    ProjectTree();
+    static std::unique_ptr<MesonProjectNode> buildTree(const Utils::FilePath &srcDir,
+                                                       const TargetsList &targets,
+                                                       const Utils::FilePaths &bsFiles);
+};
+
+} // MesonProjectManager::Internal