Add transaction pool to Aura and Babe import queue (#3225)

* Add transaction pool to babe import queue

* Add transaction pool to Babe check header

* Fix tests

* Add tx pool to Aura import_queue

* Fix tests, node-template

* Add comments regarding unused _transaction_pool

* Make tx pool optional in check_header

substrate/core/service/src/chain_ops.rs

@@ -146,7 +146,8 @@ pub fn import_blocks<F, E, R>(
 	let (mut queue, _) = components::FullComponents::<F>::build_import_queue(
 		&mut config,
 		client.clone(),
-		select_chain
+		select_chain,
+		None,
 	)?;
 
 	let (exit_send, exit_recv) = std::sync::mpsc::channel();