Use sign_with for signing grandpa's outgoing message (#6178)

* Use sign_with and stop using `Pair`

* PR feedback

* Remove clone

* Transfer ownership of public to sign_message

* Use Option

* Simplify code

* Fix error message

* Pass keystore as ref

* Pass keystore properly

* Fix tests

substrate/client/finality-grandpa/src/tests.rs

@@ -282,7 +282,7 @@ fn make_ids(keys: &[Ed25519Keyring]) -> AuthorityList {
 	keys.iter().map(|key| key.clone().public().into()).map(|id| (id, 1)).collect()
 }
 
-fn create_keystore(authority: Ed25519Keyring) -> (KeyStorePtr, tempfile::TempDir) {
+fn create_keystore(authority: Ed25519Keyring) -> (BareCryptoStorePtr, tempfile::TempDir) {
 	let keystore_path = tempfile::tempdir().expect("Creates keystore path");
 	let keystore = sc_keystore::Store::open(keystore_path.path(), None).expect("Creates keystore");
 	keystore.write().insert_ephemeral_from_seed::<AuthorityPair>(&authority.to_seed())
@@ -1050,7 +1050,7 @@ fn voter_persists_its_votes() {
 			voter_rx: TracingUnboundedReceiver<()>,
 			net: Arc<Mutex<GrandpaTestNet>>,
 			client: PeersClient,
-			keystore: KeyStorePtr,
+			keystore: BareCryptoStorePtr,
 		}
 
 		impl Future for ResettableVoter {
@@ -1136,7 +1136,7 @@ fn voter_persists_its_votes() {
 		let config = Config {
 			gossip_duration: TEST_GOSSIP_DURATION,
 			justification_period: 32,
-			keystore: Some(keystore),
+			keystore: Some(keystore.clone()),
 			name: Some(format!("peer#{}", 1)),
 			is_authority: true,
 			observer_enabled: true,
@@ -1160,10 +1160,11 @@ fn voter_persists_its_votes() {
 		);
 
 		let (round_rx, round_tx) = network.round_communication(
+			Some(keystore),
 			communication::Round(1),
 			communication::SetId(0),
 			Arc::new(VoterSet::new(voters).unwrap()),
-			Some(peers[1].pair().into()),
+			Some(peers[1].public().into()),
 			HasVoted::No,
 		);