HPCC-9238 Use a record of string<n> to display fixed length datasets

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #4470 from ghalliday/issue9238

HPCC-9238 Use a record of string<n> to display fixed length datasets

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>