Add some SSE API endpoints

[dbehnke]

We should use SSE streaming for getting updated information where it makes sense. We can leave the current api endpoints and add on and replace old functions to use it.. that way clients can "subscribe" making an http request and only receive updated data when things change. The idea here is that clients don't have to keep polling the server for updated info but instead receive as an event.

The underlying technology: https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events

An example of how events work using supermon from allstar: https://allstar.whocaresradio.com/supermon/server.php?nodes=594950,594953,594951,594952

original discord thought.. https://discord.com/channels/771492414120656907/841736165089607721/1166474029515931658