Add support for Cloudflare Load Balancer

Cloudflare Load Balancer is supported in cloudflared when using the `--lp-pool` parameter (see https://developers.cloudflare.com/argo-tunnel/reference/load-balancing/). Ex:

`$ cloudflared tunnel --hostname my.example.com --url http://localhost:8080 --lb-pool my-pool-name-goes-here`

Please add support to Hera for `--lb-pool` parameter.