Today, tailnet.Conn does not configure any DNS in Tailscale networking. In order to support a desktop native VPN to Coder workspaces, we should enhance tailnet.Conn (e.g. via the configMaps subcomponent) to be programmed with domain names and corresponding IP addresses to be served from the Tailscale DNS server.

This will allow us to eventually have client applications learn workspace agent names and IP addresses ( via #14716 ) and then program DNS entries for them into Tailscale.

In this increment, only IPv6 addresses need to be supported, and if enabled the Tailscale DNS service should respond on [fd60:627a:a42b::53]:53.