HPCC-11542 Ensure expressions in action lists are actions.

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #5983 from ghalliday/issue11542b

HPCC-11542 Ensure expressions in action lists are actions.

Reviewed-By: Jamie Noss <james.noss@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>