Make transaction pool prune transactions only of canonical blocks (#6123)

* Make tx pool aware of retracted fork blocks

* Make it compile

* Update client/transaction-pool/src/lib.rs

Co-authored-by: Nikolay Volf <nikvolf@gmail.com>

* Fix doc test

* Simplify the implementation

* Send tree route as arc to prevent heavy clones

* Switch to use `ExtrinsicHash` to make it more clear

* Fix benchmark

Co-authored-by: Nikolay Volf <nikvolf@gmail.com>

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

@@ -585,7 +585,7 @@ mod tests {
 				origin: BlockOrigin::File,
 				header,
 				is_new_best: false,
-				retracted: vec![],
+				tree_route: None,
 			}).unwrap();
 		}
 	}