Add policy for ingress host rules

[tmojlupo]

What would you like to be added:
A policy that verifies that ingress resources are created with something in spec.rules[].host and block if spec.rules[].host is empty.

Why is this needed:
If someone creates an ingress without any host specified, that ingress could become a wildcard rule and could answer for any hostname that doesn't already have an ingress rule.