HPCC-9229 Introduce a Array::swapWith(Array & other) member

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #4325 from ghalliday/issue9229

HPCC-9229 Introduce a Array::swapWith(Array & other) member

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>