Add ability to pause and/or mute all alerts from dashboard

I'd like the ability to pause and/or mute alerts from the dashboard.  Say I've got a serious topic I want to talk about, but I'm okay with the alerts still showing up... just don't want any noise.  Or if I want to put a pause on alerts like resub alerts while I talk and then let them play out later.

Once the API hook for events/alerts is added I think I can do this myself, but might be nice for others who don't want to have to interact with the API.