fix: allow customizing console redirection (#12665)

MinIO might be running inside proxies, and
console while being on another port might not be
reachable on a specific port behind such proxies.

For such scenarios customize the redirect URL
such that console can be redirected to correct
proxy endpoint instead.

fixes #12661

cmd/globals.go

@@ -45,6 +45,7 @@ import (
 	"github.com/minio/minio/internal/event"
 	"github.com/minio/minio/internal/pubsub"
 	"github.com/minio/pkg/certs"
+	xnet "github.com/minio/pkg/net"
 )
 
 // minio configuration related constants.
@@ -137,6 +138,10 @@ var (
 	// This flag is set to 'true' by default
 	globalBrowserEnabled = true
 
+	// Custom browser redirect URL, not set by default
+	// and it is automatically deduced.
+	globalBrowserRedirectURL *xnet.URL
+
 	// This flag is set to 'true' when MINIO_UPDATE env is set to 'off'. Default is false.
 	globalInplaceUpdateDisabled = false