## Ticket
Part of "#385 Defer api.odysee.com calls to their respective pages / install new"
## Change
Pull out `notification/categories` from `doNotificationList` and fetch it in Notifications Page. I don't there there are other places that need it for now.
- Re-organize the return statement of 'NotificationsPage' a bit, otherwise the entire page will reload (blink) every time the drop-down value is changed due to the 'fetching' flag.
- Retained the original behavior of (only showing a blank page + spinner) on the very first load. I think there is merit in not showing the buttons immediately (e.g. when not logged in and `/$/notifications` is accessed directly).
