Cpp{Tools,Editor}: Tests: Use QString instead of QByteArray

This is necessary in order to add tests with multi-byte UTF-8 code
points. Otherwise the initial and target source code marker positions
will be calculated on the QByteArray (test code) but used with a QString
(editor document).

Change-Id: I108961b13d32912a4d3193cf26eb59f65d296f57
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/plugins/cpptools/cpptoolstestcase.h

@@ -56,8 +56,8 @@ public:
     bool writeToDisk() const;
 
 public:
-    QByteArray m_fileName;
-    QByteArray m_source;
+    QString m_fileName;
+    QString m_source;
     char m_cursorMarker;
 };