proxyjump not taking host configuration into account

[caarlos0]

          If the Host referenced by a `ProxyJump` is just an ssh config host name (not a real host name), wishlist still fails with `lookup HOST: no such host`.  Why does it need to look up the host?

Originally posted by @curio77 in #146 (comment)

we need to lookup in the configuration files to see if the proxyjump host is defined in the config.