KubernetesClientConfiguration could support loading from string

[allantargino]

My team and I are working in k8s automation solution, where we will administrate several different k8s clusters using k8s API.

For that, we store every config yaml file in our databases in a text field (due to limitations on store it as an object).
When instantiating K8SConfiguration, it would be much better load it directly as a string into the constructor.