Draft: Envoy Gateway: Optionally manage ClientTrafficPolicy and SecurityPolicy

What does this MR do?

Envoy Gateway: Optionally manage ClientTrafficPolicy and SecurityPolicy

These can be useful e.g. to configure IP allow/denylisting and proxy protocol behaviour:

• https://gateway.envoyproxy.io/docs/tasks/security/restrict-ip-access/#create-a-securitypolicy
• https://gateway.envoyproxy.io/contributions/design/client-traffic-policy/#features--api-fields

Relates https://gitlab.com/gitlab-com/gl-infra/software-delivery/operate/team-tasks/-/issues/15

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