libedit for sftp

Summary of the new feature / enhancement

As mentioned multiple times since 2016, sftp binary shipped with Windows is still barely usable, tab completion is not hard to implement, and upstream openssh says clearly in their documentation:

--with-libedit Enable libedit support for sftp.

But in the 2016 issue (#261) where this issue had been first raised, one contributor didn't even know if

sftp autocomplete work in the Unix version of OpenSSH?

And a collaborator said auto-completion is "provided by terminal" and closed the issue! Can you please at least do some research if you have no clue how things work?

auto complete functionality is provided by the terminals (like cygwin) and not by the sftp.
sftp protocol doesn't deal with auto complete. please use terminals that support the auto complete (like cygwin).

Not to mention sftp's auto-completion has nothing to do with "terminal", no command line editing ever had anything to do with terminal at all! I'm shocked how he can be a collaborator of this repo with such limited knowledge about openssh and unix in general.

Proposed technical implementation details (optional)

--with-libedit

when building this project

Start with the Windows sftp build entry point and investigate how the upstream --with-libedit option is supported. Research libedit integration and whether the existing sftp command-line behavior can provide editing and tab completion. Done means the Windows sftp binary builds with libedit and provides the requested interactive completion behavior.