Error management. Possibility to display Kubernetes' errors when they occur.

[david-rodriguez-pd]

Hi team

Sometimes, when errors occur, we receive errors from Java or a specific library. It would be helpful to also get the errors thrown by Kubernetes to know what is going on, for instance, when the token isn't correct, the error display in the GUI isn't explicit as it displays the following message :

The Node Source had an error:
failed to execute: /home/rundeck/libext/cache/kubernetes-plugin-2.0.4-SNAPSHOT/pods-resource-model.py: Script execution failed with result: 1

It would be more helpful to display the authentication error from Kubernetes in this example.