1. Added some command line options to the wolfSFTP client to show how to
use a hardcoded automatic file transfer rather than using the command
shell. On top of that, added a script to get and put some sample files.
It was built into the wolfSFTP client to allow for using all forms of
authentication as well as using the command line password.
2. Update wolfSSH_SFTP_STAT() with clearing the error register if it is WANT_READ.