Add more information to push notification payload

[jwr1]

Is your feature request related to a problem? Please describe.
At the moment, Interstellar only displays push notification title and message. I would like to extend functionality by adding actions when a notification is tapped on, such as the default action to pull up the page a notification originated from, a mark as read action, or even a reply action.

The current push notification payload is very simple and severely limits any advanced functionality anybody would want to implement. For instance, in order to make notifications clickable and pull up the correct page, I'm going to have to parse the actionUrl property (which is just a URL to the Mbin web client) and figure out what type of notification and the related resource id is associated by the path (and hope the path never changes in the future). Other actions are completely impossible; if I want to mark a notification as read, there's no notificationId to go off of, so I wouldn't know what to send to the API.

Android also has a Message notification style that can format notifications as conversations, and it accepts author names/icons, message time, message body, etc., that I couldn't acquire without either fetching the notification data through api or attempting to parse the push notification body (which wouldn't work at all due to translations).

Describe the solution you'd like
At the very least, it'd be great if the notification payload had a notificationId property; that way, I could access any additional information that's needed by making an API request; it's not ideal, but it would work.

Ideally, the push notification would have all needed information already in the payload; that way, additional requests don't need to be made every time a notification comes in. This might not be feasible though.