Extract consensus_gossip.rs and put it in its own crate (#4284)

* Extract gossiping system from network

* Finish porting GRANDPA tests

* Try put correct engine ID

* Fix messages encoding

* Fix communication tests

* Use a threads pool to spawn stuff

* Fix compilation everywhere

* Fix bad merge conflict

* Remove dependency on async-std

* Apply suggestions from code review

Co-Authored-By: Robert Habermeier <rphmeier@gmail.com>

* More suggestions

* Remove network startup GP future

* Update to futures_timer

* adjust wait_when_behind test

* Pass correct Roles after handshake

* Revert "adjust wait_when_behind test"

This reverts commit 23cb3a0a6d25ed732c2cd648607bc44ef2ab0919.

* Crate root documentation

* Remove MessageRecipient

* Address concerns

* Fix more concerns

* Forgot Cargo.lock

substrate/client/finality-grandpa/src/communication/gossip.rs

@@ -83,7 +83,7 @@
 //! We only send polite messages to peers,
 
 use sp_runtime::traits::{NumberFor, Block as BlockT, Zero};
-use network::consensus_gossip::{self as network_gossip, MessageIntent, ValidatorContext};
+use network_gossip::{GossipEngine, MessageIntent, ValidatorContext};
 use network::{config::Roles, PeerId, ReputationChange};
 use codec::{Encode, Decode};
 use fg_primitives::AuthorityId;
@@ -1459,29 +1459,26 @@ pub(super) struct ReportStream {
 impl ReportStream {
 	/// Consume the report stream, converting it into a future that
 	/// handles all reports.
-	pub(super) fn consume<B, N>(self, net: N)
+	pub(super) fn consume<B>(self, net: GossipEngine<B>)
 		-> impl Future<Item=(),Error=()> + Send + 'static
 	where
 		B: BlockT,
-		N: super::Network<B> + Send + 'static,
 	{
 		ReportingTask {
 			reports: self.reports,
 			net,
-			_marker: Default::default(),
 		}
 	}
 }
 
 /// A future for reporting peers.
 #[must_use = "Futures do nothing unless polled"]
-struct ReportingTask<B, N> {
+struct ReportingTask<B: BlockT> {
 	reports: mpsc::UnboundedReceiver<PeerReport>,
-	net: N,
-	_marker: std::marker::PhantomData<B>,
+	net: GossipEngine<B>,
 }
 
-impl<B: BlockT, N: super::Network<B>> Future for ReportingTask<B, N> {
+impl<B: BlockT> Future for ReportingTask<B> {
 	type Item = ();
 	type Error = ();