Move grandpa crates to consensus folder (#13458)

* Move grandpa under consensus dir
* Rename grandpa folder
* Finish grandpa renaming
* Minor tweaks
* Cargo fmt
* Adjust path to chain spec

substrate/client/consensus/grandpa/src/notification.rs

@@ -0,0 +1,43 @@
+// This file is part of Substrate.
+
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+use sc_utils::notification::{NotificationSender, NotificationStream, TracingKeyStr};
+
+use crate::justification::GrandpaJustification;
+
+/// The sending half of the Grandpa justification channel(s).
+///
+/// Used to send notifications about justifications generated
+/// at the end of a Grandpa round.
+pub type GrandpaJustificationSender<Block> = NotificationSender<GrandpaJustification<Block>>;
+
+/// The receiving half of the Grandpa justification channel.
+///
+/// Used to receive notifications about justifications generated
+/// at the end of a Grandpa round.
+/// The `GrandpaJustificationStream` entity stores the `SharedJustificationSenders`
+/// so it can be used to add more subscriptions.
+pub type GrandpaJustificationStream<Block> =
+	NotificationStream<GrandpaJustification<Block>, GrandpaJustificationsTracingKey>;
+
+/// Provides tracing key for GRANDPA justifications stream.
+#[derive(Clone)]
+pub struct GrandpaJustificationsTracingKey;
+impl TracingKeyStr for GrandpaJustificationsTracingKey {
+	const TRACING_KEY: &'static str = "mpsc_grandpa_justification_notification_stream";
+}