Move XElementAccess Java tests to C++ for ScCellFieldsObj.

Change-Id: I140cb1f1d5f9cbccfd4dbb43d37c9cd48b7346e8
Reviewed-on: https://gerrit.libreoffice.org/64794
Tested-by: Jenkins
Reviewed-by: Jens Carl <j.carl43@gmx.de>