Add "Mark read" intent to article notifications

[jocmp]

Comment

[PhilC813]

Maybe this would deserve a separate entry, but something that could be relevant to implement simultaneously is for notifications to be dismissed when their associated article is read from within the app.

Currently, let's say that you have notifications for 6 unread articles; you open the first through the notification, but you access the others from within the app. After you've done reading them, their notification will still be present in the notifications tray, requiring that you dismiss them manually.