Emit 'app-close' event when clicking the modal background in Embedded Onboard

You can now emit an ‘app-close’ event whenever onClose is called in Embedded Onboard. Previously, only the `X` button in Embedded Onboard would fire the `app-close` event. Now, clicking the Embedded Onboard modal background will fire this event as well. This fix is part of our continuous process of improving and providing more visibility into the state of our systems.

See our guide to learn more about Onboard.