Move over to Kubernetes and make SSL and message hub creation super easy

[mreider]

@omarst910 is working on some Kubernetes deployments. When he is done, we will migrate our message hub and user hub postgres databases to the new postgres instances on kubernetes. Then we will cut DNS from the current Digital Ocean VM running docker, to this new Kubernetes cluster.

He is adding cert-manager, which will replace our need for the Caddy Server.
https://cert-manager.io/docs/

After he is done, we can start doing some interesting things.

For instance, we could host message hubs for people pretty easily, if they are willing to pay us, rather than pay a cloud vendor directly. We could build a simple Github Action that creates a random subdomain off of koto.at, and then deploys a new kubernetes pod with a message hub for them.

Afterwards we could auto-register the new message hub in the same Github Action so the whole thing is totally seamless to the user.