Hook the new (1.11.0 or newer) libssh2 support for setting a read timeout
into the SERVER_RESPONSE_TIMEOUT option. With this done, clients can use
the standard curl response timeout setting to also control the time that
libssh2 will wait for packets from a slow server. This is necessary to
enable use of very slow SFTP servers.
Signed-off-by: Daniel Silverstone <daniel.silverstone@codethink.co.uk>
Closes#10965