Perform network tasks for schedule notifications

Once `scheduleLocalNotification()` is set, the data can't be updated until the user opens the app and sets it again.

Performing a javascript task for `scheduledNotification()` would be extremely useful for updating a news feed and notifying the user of the latest.

Is this something in the works?

For example something like this would be extremely useful:

```
FCM.scheduleLocalNotification({
fire_date: new Date().getTime(),
repeat_interval: "day",
id: "randomId",
schedule_task: this.fetchLatestFeed(), <---- like this
});

async fetchLatestFeed() {
var url = 'someUrl...';
var data = await fetch(url).then((result)=> result);
var newContent = {title: data[0].title, body: data[0].body, big_text: etc etc.... };
return newContent;
}
```

The schedule_task could listen for the title and body objects and the update it accordingly?

I'm sure there's a better way than this, but just throwing an idea/request out there. it would be awesome to have something like this.

I know there's headlessJS, but the documentation is extremely poor for coders with no java skills.