POI：bug 58633 comment 5 and comment 6: add unit test coverage for CellUtil.java; throw exception of Cell does not belong to workbook for some methods
POI：bug 58633 comment 5 and comment 6: add unit test coverage for CellUtil.java; throw exception of Cell does not belong to workbook for some methods

tonyqus/npoi,antony-liu/npoi