HPCC-8862 Add support for csv escape characters to sprayVariable

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #4044 from ghalliday/issue8862

HPCC-8862 Add support for csv escape characters to sprayVariable

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>