HPCC-8589 Add tests for dictionary in key payload in keyed join

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #4003 from richardkchapman/dict-keyedjoin-test

HPCC-8589 Add tests for dictionary in key payload in keyed join

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>