HPCC-12136 Embedded MySQL has no means to specify port

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #6383 from richardkchapman/mysql-port

HPCC-12136 Embedded MySQL has no means to specify port

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>