Add method to dismiss Simulator request to save password

See logic duplicated between https://github.com/wordpress-mobile/WordPress-iOS/pull/20583 and https://github.com/woocommerce/woocommerce-ios/pull/9555.

Despite opening this issue, I'm a bit on the fence on this one. It would be handy to hide the logic away here, but at the same time it's really just a couple of lines and it might be easier to keep duplicating it across apps and let each consumer adapt its own version.