HPCC-8802 Implement RECORDOF(dictionary)

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #3967 from ghalliday/issue8802

HPCC-8802 Implement RECORDOF(dictionary)

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>