How to set direct_response (Return an arbitrary HTTP response directly, without proxying)

[yuyicai]

Description:
How to set direct_response using envoy gateway?
The envoy proxy native configuration:

route_config:
  virtual_hosts:
    - name: direct
      domains:
        - "www.example.com"
      routes:
        - match:
            prefix: "/404"
          direct_response: 
            status: 404

[optional Relevant Links:]
https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/route/v3/route_components.proto#envoy-v3-api-field-config-route-v3-route-direct-response

https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/route/v3/route_components.proto#envoy-v3-api-msg-config-route-v3-directresponseaction

[arkodg]

dup of #2714
the work is in progress #4334 and should hopefully land in v1.2 (end Oct 2024)