feat: show "read" notifications

[setchy]

Closes #708

Add new Notification Settings to show all notifications (defaulted to off).

When set, notification rows will be opaque when read.

The mark as read button both at the Repository and Notification level are conditional based on whether the notification(s) are unread or not.

Some things to note

1. we don't support fetching more than the first page of REST API results, so the notifications will be maxed at 50
2. the API returns all notifications (unread, read, done)

[setchy]

TODO - need to find a solution to recalculate the unread notification count