Set up a client for Twitch EventSub/PubSub events

[dmatech1]

Twitch's EventSub is probably the best way of getting comprehensive events from my channel (particularly those that don't show up in IRC). Unfortunately, it requires TLS and port 443. Fortunately, I don't think my ISP blocks that port, and I should be able to create the certificates easily enough.

Alternatively, PubSub works without requiring that I listen on a port, but I don't know if the events are as comprehensive as EventSub, and I don't know if it's as robust with respect to missed events.