TUN-8052: Update go to 1.21.5

Also update golang.org/x/net and google.golang.org/grpc to fix vulnerabilities,
although cloudflared is using them in a way that is not exposed to those risks

vendor/google.golang.org/appengine/internal/identity.go

@@ -5,9 +5,8 @@
 package internal
 
 import (
+	"context"
 	"os"
-
-	netcontext "golang.org/x/net/context"
 )
 
 var (
@@ -23,7 +22,7 @@ var (
 
 // AppID is the implementation of the wrapper function of the same name in
 // ../identity.go. See that file for commentary.
-func AppID(c netcontext.Context) string {
+func AppID(c context.Context) string {
 	return appID(FullyQualifiedAppID(c))
 }
 
@@ -35,7 +34,7 @@ func IsStandard() bool {
 	return appengineStandard || IsSecondGen()
 }
 
-// IsStandard is the implementation of the wrapper function of the same name in
+// IsSecondGen is the implementation of the wrapper function of the same name in
 // ../appengine.go. See that file for commentary.
 func IsSecondGen() bool {
 	// Second-gen runtimes set $GAE_ENV so we use that to check if we're on a second-gen runtime.