Set CreateNoWindow=true in RunProcessAndWaitForExit (modelcontextprotocol#462)

Author: stephentoub

src/ModelContextProtocol/ProcessHelper.cs

@@ -107,6 +107,7 @@ private static int RunProcessAndWaitForExit(string fileName, string arguments, T
             RedirectStandardOutput = true,
             RedirectStandardError = true,
             UseShellExecute = false,
+            CreateNoWindow = true,
         };
 
         stdout = null;