GHSA-mggc-4xg6-vcxf: SSH.NET: ScpClient allows server-side RCE via default SCP path handling

## Summary Default SCP remote-path handling places caller-supplied paths into the command that runs scp on the server. On a shell-based server that command is interpreted by a shell, so an attacker-influenced path that is not quoted to suit that shell can execute as a command as the authenticated SSH user. SSH.NET provides `ScpClient.RemotePathTransformation` to control escaping behaviour (defaulting to `RemotePathTransformation.DoubleQuote`) but cannot guarantee safety for arbitrary remote command interpreters. This is inherent to running scp over a remote shell (cf. CVE-2020-15778). …