Add command for checking cluster network policy conformance

[maxbischoff]

Using the e2e manifests, we could also provide another command illuminatio conformance-test, which supplies these e2e manifests and checks that the network traffic in those setup behaves as expected. This would enable cluster operators that don't have network policies in their clusters yet, to check, that their setup is correctly enforcing various kinds of policies. That command could also be used for https://github.com/inovex/illuminatio/issues/38. It's implementation should not duplicate https://github.com/inovex/illuminatio/issues/29.