Deleting namespaces should have a warning

[jinnovation]

Deleting namespaces is dangerous. It is, however, extremely easy to do so in Kele. For example, hitting k in kele-list when the displayed resource kind is Namespace is only blocked by a yes-or-no prompt.

For these cases, we should introduce additional friction to prevent users from shooting themselves in the foot. Something like forcing them to type the full namespace out in order to proceed with deletion.