Add SSH-Connection JumpHost Command Configuration

[Vonor]

As it is right now, the Jumphost Setting will use the sshcommand to connect to the jumphost and then use the ssh command to connect to the remote host.

I work in an environment where I have to connect to a 2fa enabled Jumphost and then use a different command to connect to the actual host.

Would be great to be able to have Tabby be able to configure that different command