HPCC-12708 Optimize jset and provide countTrailingZeros() helpers

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-12708 Changes following review.

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #6740 from ghalliday/issue12708

HPCC-12708 Optimize jset and provide countTrailingZeros() helpers

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>