Hi I'm developing a macOS desktop app. I'd like my application, when installed, to have a custom icon on the top right system menu bar (near where the time and wifi icons are). An example of this is TunnelBear icon + UI (https://imgur.com/a/DSullUS). Can someone point me to the APIs needed for building a feature like this? (Bonus points: I'd like the UI displayed onClick to be rendered by Flutter (which the main app views are using), any idea how that could be done?)