chore: migrate to coder/websocket 1.8.12 (#15898)

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.

tailnet/derp.go

@@ -8,9 +8,9 @@ import (
 	"strings"
 	"sync"
 
-	"nhooyr.io/websocket"
 	"tailscale.com/derp"
-	"tailscale.com/net/wsconn"
+
+	"github.com/coder/websocket"
 )
 
 // WithWebsocketSupport returns an http.Handler that upgrades
@@ -60,7 +60,7 @@ func WithWebsocketSupport(s *derp.Server, base http.Handler) (http.Handler, func
 				c.Close(websocket.StatusPolicyViolation, "client must speak the derp subprotocol")
 				return
 			}
-			wc := wsconn.NetConn(ctx, c, websocket.MessageBinary)
+			wc := websocket.NetConn(ctx, c, websocket.MessageBinary)
 			brw := bufio.NewReadWriter(bufio.NewReader(wc), bufio.NewWriter(wc))
 			s.Accept(ctx, wc, brw, r.RemoteAddr)
 		}), func() {

tailnet/test/integration/integration.go

@@ -26,7 +26,6 @@ import (
 	"github.com/google/uuid"
 	"github.com/stretchr/testify/require"
 	"golang.org/x/xerrors"
-	"nhooyr.io/websocket"
 	"tailscale.com/derp"
 	"tailscale.com/derp/derphttp"
 	"tailscale.com/tailcfg"
@@ -40,6 +39,7 @@ import (
 	"github.com/coder/coder/v2/tailnet"
 	tailnetproto "github.com/coder/coder/v2/tailnet/proto"
 	"github.com/coder/coder/v2/testutil"
+	"github.com/coder/websocket"
 )
 
 type ClientNumber int