Test whether hiding UI still works on Android 10
Android 10 places new restrictions on background apps starting activities:
Check whether BriarService#hideUi(), which is called on low memory and when the device shuts down, works under the following circumstances:
- Briar is visible in recent apps
- Briar has been cleared from recent apps but is still running
It's not a big deal if hideUi() stops working, as long as we don't get a crash or unexpected behaviour when calling it or when relaunching the app.