[Bugfix] Hide kubecontext prompt if there is no current context

[tdmalone]

This hides the kubecontext prompt if there is no current context set in ~/.kube/config. Essentially, this prevents a namespace from being shown all on its own.

BEFORE this PR - no context set:

AFTER this PR - no context set:

BEFORE & AFTER this PR (i.e. no change) - context set:

[mvaldesdeleon]

Would be nice if this got merged, as I just implemented the same feature and came here looking for unmerged PRs before submitting my own.