Utils: Add tst_filepath

Moves all tests that are applicable only to FilePath over from
tst_fileutils.

Change-Id: Ic331e1470a7479ee2f8ba38baec84124982a000a
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/libs/utils/filepath.h

@@ -293,6 +293,9 @@ public:
     std::function<void(const FilePath &, const Environment &)> openTerminal;
 };
 
+// For testing
+QTCREATOR_UTILS_EXPORT QString doCleanPath(const QString &input);
+
 } // Utils
 
 Q_DECLARE_METATYPE(Utils::FilePath)