HPCC-9810 Add test case for transfer to/from unicode

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #4714 from ghalliday/issue9810

HPCC-9810 Add test case for transfer to/from unicode

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>