Adaptations for CVE-2025-9615

See also: https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/2325 Any file access within the plugin should take implement safe access. At the moment this boils down to: * Key authentication access (accessing the private key) * Known hosts file Up until then, with the deployed NetworkManager version, only "admin" users (belonging to `wheel`, or equivalent) will be able to operate those connections.