MeshTLS `spec.rules` to do the actual configuration

[Automaat]

Description

#12366 introduces new API, we should make it work.

This is the first implementation of spec.rules so it's going to cover common parts with other policies:

• policy-gen tools
• changes in common structs like

  kuma/pkg/core/xds/matched_policies.go

  Line 13 in a9be038

  type TypedMatchingPolicies struct {