Collaborative notifications

> As an end user of the application, I need to reduce the total amount of notifications in my life, in order to reduce distraction.

Currently, when having two Outline tabs open and dismissing all notifications in one, they will still show up in the other. If notifications could use the collaborative facilities, their state could be synced via the CRDT. This could allow to dismiss notifications in all browser tabs without the need for a reload, when they were already dismissed in one.