policy: add new Policy type
policy: add new Policy type

This groups separate types that encode resolved policy, e.g. L4Policy,
CIDRPolicy, into one structure.

Signed-off by: Ian Vernon <ian@cilium.io>

tklauser/cilium,michi-covalent/cilium,tklauser/cilium,scanf/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,scanf/cilium,tgraf/cilium,scanf/cilium,tgraf/cilium,tklauser/cilium,tklauser/cilium,scanf/cilium,scanf/cilium,michi-covalent/cilium,tgraf/cilium,cilium-team/cilium,tklauser/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,tgraf/cilium,cilium/cilium,cilium-team/cilium,michi-covalent/cilium,scanf/cilium,tgraf/cilium,scanf/cilium