Migrates us to `coder/websocket` v1.8.12 rather than `nhooyr/websocket` on an older version.
Works around https://github.com/coder/websocket/issues/504 by adding an explicit test for `xerrors.Is(err, io.EOF)` where we were previously getting `io.EOF` from the netConn.
fixes#14881
Our handlers for streaming logs don't read from the websocket. We don't allow the client to send us any data, but the websocket library we use requires reading from the websocket to properly handle pings and closing. Not doing so can [can cause the websocket to hang on write](https://github.com/coder/websocket/issues/405), leaking go routines which were noticed in #14881.
This fixes the issue, and in process refactors our log streaming to a encoder/decoder package which provides generic types for sending JSON over websocket.
I'd also like for us to upgrade to the latest https://github.com/coder/websocket but we should also upgrade our tailscale fork before doing so to avoid including two copies of the websocket library.
