Forward proxy support for NGINX Plus R34

[sjberman]

With R34, NGINX Plus allows NGINX customers to send their license usage telemetry to F5 via an existing enterprise forward proxy in their environment.

NGF should support these fields so a user can configure NGINX Plus to forward usage reports via a forward proxy solution.

mgmt {
    proxy HOST:PORT;
    proxy_username USER;    #optional
    proxy_password PASS;    #optional
}

https://nginx.org/en/docs/ngx_mgmt_module.html

Acceptance

• allow users to configure forward proxy fields for usage reports when running NGINX Plus