android notif: Inline wix's setNotificationOpenedListener.
android notif: Inline wix's setNotificationOpenedListener.

This `getData` stuff isn't a great API for this; it'll be
easier to fix once it's entirely within our control.

vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile