Run arti hidden service without socks/dns proxy

Summary

When starting arti without any subcommand, it shows help. When starting arti with proxy port and dns port set to 0 (disable), it fails with below error

2024-08-26T18:50:46Z  WARN arti: No proxy port set; specify -p PORT (for `socks_port`) or -d PORT (for `dns_port`). Alternatively, use the `socks_port` or `dns_port` configuration option.

What is the expected behavior?

1. Allow arti proxy, to run onion service without socks or dns proxy
2. Add new subcommand arti hss to just run onion service