Implement GraphQL endpoint to fetch list of uncleared notifications

[jptrindade]

This is the call that the frontend uses:

GET api/v2/notification?limit=100&filter.cleared=false
Get the list of uncleared notifications, if the list contains an unread or an error unread, we adjust the color of the icon button in the header.

The list of notifications is displayed within the drawer that slides open when clicking on the notification icon.

This might now require paging (or just limiting) and filtering on cleared