Rewrite of Python cockpit-auth-ssh-key in Rust.

Pick a ssh key which has a passphase, the example below uses ~/.ssh/id_rsa. Add the pub key to ~/.ssh/authorized_keys on some target host that has cockpit bridge installed. Here the default-bastion.conf is replaced with one that points to the Rust cockpit-auth-ssh-key.

$ cargo build

$ docker run -d --rm \
  --name cockpit-bastion \
  -e RUST_LOG=debug \
  -e COCKPIT_SSH_KEY_PATH=/id_rsa \
  -v $HOME/.ssh/id_rsa:/id_rsa:ro \
  -v $PWD/default-bastion.conf:/container/default-bastion.conf \
  -v $PWD/target/debug/:/work \
  -p 9090:9090 \
  quay.io/cockpit/ws

$ docker logs -f cockpit-bastion

$ firefox https://localhost:9090

In the browser dialog, set User name to the user of the target host. Set Password to the passphrase for the ssh key. Set Connect to to the target host.