check-kube-pods-service-available does not have namespace option

[drsoares]

I have the following sceneario, I have two services with the same name but in different namespaces, however I want to have different checks for both services.

Currently the check-kube-pods-service-available check requires a service list, which doesn't allow me to have different checks per namespace.

I'm happy to perform the necessary changes to support it.

[jakerobb]

I would also like a namespace option, but for a slightly different use case: we'd like to run the same check on all services in a namespace without having to know the list of services in advance.