ClangFormat: Refactor code

Reorder some functions, remove code duplication.

Change-Id: I33e118e567dee7db622bbc99e6a7c500db54e5c5
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/libs/utils/textutils.h

@@ -59,5 +59,9 @@ QTCREATOR_UTILS_EXPORT int utf8NthLineOffset(const QTextDocument *textDocument,
                                              const QByteArray &buffer,
                                              int line);
 
+QTCREATOR_UTILS_EXPORT LineColumn utf16LineColumn(const QByteArray &utf8Buffer, int utf8Offset);
+QTCREATOR_UTILS_EXPORT QString utf16LineTextInUtf8Buffer(const QByteArray &utf8Buffer,
+                                                         int currentUtf8Offset);
+
 } // Text
 } // Utils