network: unplug stateroot service from the Server

Notice that it makes the node accept Extensible payloads with any category
which is the same way C# node works. We're trusting Extensible senders,
improper payloads are harmless until they DoS the network, but we have some
protections against that too (and spamming with proper category doesn't differ
a lot).

pkg/consensus/consensus_test.go

@@ -351,7 +351,7 @@ func TestService_OnPayload(t *testing.T) {
 	p.encodeData()
 
 	// sender is invalid
-	srv.OnPayload(&p.Extensible)
+	require.NoError(t, srv.OnPayload(&p.Extensible))
 	shouldNotReceive(t, srv.messages)
 
 	p = new(Payload)
@@ -359,7 +359,7 @@ func TestService_OnPayload(t *testing.T) {
 	p.Sender = priv.GetScriptHash()
 	p.SetPayload(&prepareRequest{})
 	require.NoError(t, p.Sign(priv))
-	srv.OnPayload(&p.Extensible)
+	require.NoError(t, srv.OnPayload(&p.Extensible))
 	shouldReceive(t, srv.messages)
 }