This fix adds `--dns-add`, `--dns-rm`, `--dns-opt-add`, `--dns-opt-rm`, `--dns-search-add` and `--dns-search-rm` to `service update`. An integration test and a unit test have been added to cover the changes in this fix. Signed-off-by: Yong Tang <yong.tang.github@outlook.com> Upstream-commit: a39c0cf00780c021e98f638ab7edf151a8adb789 Component: engine