Add nav/tramp-to-term

Hello,

This is what I have for now and it works. It raises a few questions that needs to be solved before you can merge this:

* is the name ok?
* as you can see I found a little trick around `:program-args` to run a command after ssh login is successful. This fixes the problem you have currently with `:init-script` that doens't work for ssh connection that requires you to input the password. Would you be interested in refactoring `init-script` around this trick? A neater solution would maybe be to deted `password:` prompt and input them in the minibuffer like TRAMP does.