Parse remote user name from currently open TRAMP buffer

[OknoLombarda]

Is your feature request related to a problem? Please describe.

Now, when I try to jack-in from TRAMP buffer, CIDER tries to open SSH tunnel using current local user name, even though TRAMP buffer uses a different user to connect

Describe the solution you'd like

Instead of manually formatting path here
https://github.com/clojure-emacs/cider/blob/master/nrepl-client.el#L573
we could use (buffer-file-name) to get current buffer's name to get all necessary properties for connection

Additional context

I'm trying to connect to a remote PC with username that is different from the one on my local machine. I could, of course, just create user with this name on a remote PC, but I don't really want to create a separate user just to be able to connect from CIDER. Also, there is this issue, that could also be resolved by applying proposed solution