HPCC-9465 Preserve the case of parameters for external functions

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPPC-9465 Use the preserved case for embedded language parameters

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-9465 Fix various issues picked up in the code review

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #4492 from ghalliday/issue9464b

HPCC-9465 Preserve the case of parameters for external functions

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>