Allow Windows(and other !HAVE_TCP_CONGESTION clients) client set remote's congestion control algorithm

Currently, the guest can set the congestion control algorithm for both sides with `-C` if testing a Linux remote with a Linux guest.

But for Windows (and probably macOS?), which lacks `HAVE_TCP_CONGESTION`, it's unable to set the remote's congestion, which can be useful while running under reversed mode (-R) with a Linux or FreeBSD remote.

Maybe we can provide an option dedicated to setting remote congestion or just reuse `-C` with reduced ability on non `HAVE_TCP_CONGESTION` clients?