Decide if we want to open Android notification settings from the app

The app can detect if notifications have been disabled. In that case, we could display a message to the user explaining why are they needed with a button to open the settings to enable them (and a "Don't ask me again" option). This is done with the intent ACTION_APP_NOTIFICATION_SETTINGS.

In the same way, the app can detect if "Alarms & reminders" have been disabled (this is needed for local notifications). This is done with ACTION_REQUEST_SCHEDULE_EXACT_ALARM.