signalling server update

SignallingWebServer/platform_scripts/cmd/setup_coturn.bat

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+@Rem Copyright Epic Games, Inc. All Rights Reserved.
+
+@echo off
+
+@Rem Set script location as working directory for commands.
+pushd "%~dp0"
+
+@Rem Look for CoTURN directory next to this script
+if exist coturn\ (
+  echo CoTURN directory found...skipping install.
+) else (
+  echo CoTURN directory not found...beginning CoTURN download for Windows.
+
+  @Rem Download nodejs and follow redirects.
+  curl -L -o ./turnserver.zip "https://github.com/mcottontensor/coturn/releases/download/v4.5.2-windows/turnserver.zip"
+
+  @Rem Unarchive the .zip to a directory called "turnserver"
+  mkdir coturn & tar -xf turnserver.zip -C coturn
+
+  @Rem Delete the downloaded turnserver.zip
+  del turnserver.zip
+)
+
+@Rem Pop working directory
+popd