Show notification count in title

[ColdHeat]

Show a notification count in the title to make it clearer when people should go read a notification.

This needs to be synced across all CTFd tabs so it's a little tricky.

[ColdHeat]

This actually doesn't work because you need to send messages between all the browser tabs using the window controller. The notification count is actually currently broken because this isn't how it currently works.

[ColdHeat]

A service worker may actually be able to workaround the connection limit but I'm not sure if the browser compatibility or whether SSE works well within a service worker.