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

[fakeboboliu]

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?

[davidBar-On]

Submitted PR #1897 with a suggest enhancement to add setting the server's TCP congestion control algorithm, even when setting the algorithm by the client is not supported.