Leverage appProtocol from K8S 1.18+

[jakubdyszkiewicz]

Summary

Kubernetes 1.18 introduced appProtocol field in Service. We can use it for choosing protocol instead of placing annotations.
https://kuma.io/docs/0.5.0/policies/http-support-in-kuma/

[tharun208]

ok, appProtocol has been available for ga from Nov 2020. @jakubdyszkiewicz I have a doubt, do we need to support backward compatibility for this, I don't think so because the change will be on the policy and the user can re-configure it, once it is released.

[jakubdyszkiewicz]

Yes, we need to support also annotations. It will take a long time to support only K8S 1.18+

[tharun208]

so, once this pr is merged, deprecating annotations support is introduced as a separate pr or any other approach like introducing feature toggles?

[lobkovilya]

Hey @tharun208! I think we should give support for both ways of providing the protocol, and it makes more sense to me to do so in a single pr.