Bookmarks Refactor

- Don't do async loading stuff
- Move bookmarkmanager to damus state
- Remove bookmarks update notififcation and switch to observed object
- Switch api to use events explicitly instead of strings

damus/Util/Notifications.swift

@@ -101,9 +101,6 @@ extension Notification.Name {
     static var update_stats: Notification.Name {
         return Notification.Name("update_stats")
     }
-    static var update_bookmarks: Notification.Name {
-        return Notification.Name("update_bookmarks")
-    }
     static var zapping: Notification.Name {
         return Notification.Name("zapping")
     }