Encode ArtiPath information in SSH key comment fields.
The comment field is currently unused https://gitlab.torproject.org/tpo/core/arti/-/blob/4ec6e3aaf124f6eb7c43d59d9b19885dfcc2f467/crates/tor-keymgr/src/keystore/arti.rs#L146-147
The comment should probably contain ArtiPath
of the key