updated logic to use durable buffer path if provided

Author: virajdere

agent/Modules/MTConnect.NET-AgentModule-MqttRelay/Module.cs

@@ -345,6 +345,7 @@ private static string GetLastSentSequenceFilePath(IAgentApplicationConfiguration
             {
                 baseDir = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, baseDir);
             }
+            Directory.CreateDirectory(baseDir);
             return Path.Combine(baseDir, LastSentSequenceFileName);
         }