Improve TF Agent : detect jobs stuck in Checking Status

Sometimes it happens that some jobs get stuck in 'Checking' Status. In this case the transformation never completes, since the TFAgent reschedules jobs only when all jobs are in a final status. So we should add to the Agent the functionality of detecting such jobs and take some action. In order to make the jobs passing from Checking to Waiting Status, usaully it's enough to restart the WMS_Optimizer executors. We should decide if we want that the Agent just generates an alert so that the operator takes the necessary action or if it restarts the executors itself.