CLI doesn't have config file like olm

### Describe the Bug

This is a security issue as the client id and secret are always available in `/proc//environ` or in `ps` output.

### Environment

- OS Type & Version: (e.g., Ubuntu 22.04) Any Linux distro
- Pangolin Version: Latest
- Gerbil Version: Latest
- Traefik Version: Latest
- Newt Version: Latest
- Client Version: (if applicable)

### To Reproduce

Run pangolin CLI as per the docs provided (including systemd unit) on site, check ps auxf | grep -i pangolin output

### Expected Behavior

If this is going to be used for config on Linux machines, there needs to be a mechanism for passing secrets that doesn't expose on CLI or otherwise