Summary of the new feature/enhancement

https://github.com/libfuse/sshfs enables mounting a SFTP endpoint as a local filesystem. Seems like we should be able to use this concept with a PSProvider thus enabling something like:

cd SFTP:
# no creds passed as using pubkey auth
SFTP:> Connect-SftpServer -HostName foo
cd foo
SFTP:/foo>

Proposed technical implementation details (optional)

Since we want this to be cross platform, we shouldn't use sshfs linked above. Instead, we should be able to just use sftp.exe directly with some check that it is available. This will work on Windows with OpenSSH installed.