HPCC-9974 Add self-test option to ecl-bundle

New ecl-bundle selftest subcommand

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #4845 from richardkchapman/ecl-bundle-tests

HPCC-9974 Add self-test option to ecl-bundle

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>