Extend Notifications API and return pinned notifications by default (#12164) (#12232)

Extend Notifications API and return pinned notifications by default (#12164) (#12232)

Backport #12164

This PR extends the notifications API to allow specific notification statuses to be searched for and to allow setting of notifications to statuses other than read.

By default unread and pinned statuses will be returned when querying for notifications - however pinned statuses will not be marked as read.

Close #12152

Signed-off-by: Andrew Thornton art27@cantab.net