Webhooks should have better names

[erikgb]

What

When attempting to delete a namespace with subnamespaces, this is rejected by the webhook - which is good. But I think webhooks should be named properly - so a user can understand better what's going on.

$ k delete namespaces erikbo
Error from server (Forbidden): admission webhook "vnamespace.kb.io" denied the request: child namespaces exist

How

Describe how to address the issue.

Checklist

• Finish implementation of the issue
• Test all functions
• Have enough logs to trace activities
• Notify developers of necessary actions

[zeroalphat]

@erikgb
As your feedback, it looks like it should be fixed.
We will fix it.