* Extend notifications API and return pinned notifications in notifications list

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

* fix swagger

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

* Fix swagger again

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

* fix test

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

* remove spurious debugs

* as per @6543

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

* Update models/notification.go

* as per @6543

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

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

If the browser supports EventSource switch to use this instead of
polling notifications.

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