Merge pull request #4026 from richardkchapman/roxierow-move

HPCC-8881 Move roxierow into thorhelper dll

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>
HPCC-8556 Refactor const char * query functions from helpers

Return roxiemem-allocated strings rather than having to store in context in
order to release.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-8556 Refactor const char * query functions from helpers

Rename some queryXXX functions to getXXX and support values that are not
compile-time constant.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-8556 Refactor const char * query functions from helpers

Final batch

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>