Create a proxy
[Required authorization] Route required privileges: fleet-settings-all.
POST /api/fleet/proxies
curl \ --request POST 'https://<KIBANA_URL>/api/fleet/proxies' \ --header "Authorization: $API_KEY" \ --header "Content-Type: application/json" \ --header "kbn-xsrf: true" \ --data '{"certificate":"string","certificate_authorities":"string","certificate_key":"string","id":"string","is_preconfigured":false,"name":"string","proxy_headers":{},"url":"string"}'