Authentication of PeerIds in authority discovery records (#10317)

* Consolidating test and production code

* Signing/verifying authority discovery records with PeerId

Unsigned records cannot be rejected yet, they just produce
a warning in the log.

* Upgrading to libp2p 0.40

* libp2p::identity and sp_core::crypto Ed25519 are compatible

* Rejecting authority records unsigned by peer id can be configured

* Fixes based on review comments

* No command-line argument needed

* info was still too much spam in the logs

* Added tests for both strict and loose validation

* Fixing based on review comments

* Pierre preferred a signing method

* Ooops, I need to slow down

* Update bin/node/cli/src/service.rs

* Reexport libp2p crypto used in sc-network

* Added proto3 compatibility tests. And import noise.

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/client/authority-discovery/src/worker/schema/dht-v2.proto

@@ -0,0 +1,23 @@
+syntax = "proto3";
+
+package authority_discovery_v2;
+
+// First we need to serialize the addresses in order to be able to sign them.
+message AuthorityRecord {
+	// Possibly multiple `MultiAddress`es through which the node can be 
+	repeated bytes addresses = 1;
+}
+
+message PeerSignature {
+	bytes signature = 1;
+	bytes public_key = 2;
+}
+
+// Then we need to serialize the authority record and signature to send them over the wire.
+message SignedAuthorityRecord {
+	bytes record = 1;
+	bytes auth_signature = 2;
+	// Even if there are multiple `record.addresses`, all of them have the same peer id.
+	// Old versions are missing this field, so `optional` will provide compatibility both ways.
+	optional PeerSignature peer_signature = 3;
+}