SeaweedFS: Unauthenticated SSRF with response read-back via VolumeServer.FetchAndWriteNeedle

Impact VolumeServer.FetchAndWriteNeedle fetches a caller-supplied remote endpoint and writes the response into a needle. Before 4.24 this RPC performed no authentication and no validation of the target, so anyone able to reach a volume server's gRPC port could coerce the server into issuing...