Network sync refactoring (part 2) (#11322)

* Move `api.v1.proto` schema into new crate `sc-network-sync`

* Move `sc_network::protocol::sync::state` module into `sc_network_sync::state`

* Move `sc_network::protocol::sync::blocks` module into `sc_network_sync::blocks` and some data structures from `sc_network::protocol::message` module into `sc_network_sync::message`

* Move some data structures from `sc_network::config` and `sc_network::request_responses` into new `sc-network-common` crate

* Move `sc_network::protocol::sync::warm` and `sc_network::warp_request_handler` modules into `sc_network_sync`

* Move `client/network/sync/src/lib.rs` to `client/network/sync/src/lib_old.rs` to preserve history of changes of the file in the next commit

* Move `client/network/src/protocol/sync.rs` on top of `client/network/sync/src/lib.rs` to preserve history of changes

* Move `sc_network::protocol::sync` to `sc_network_sync` with submodules, move message data structures around accordingly

* Move `sc_network::block_request_handler` to `sc_network_sync::block_request_handler`

* Move `sc_network::state_request_handler` to `sc_network_sync::state_request_handler`

* Add re-exports for compatibility reasons

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/client/network/common/src/config.rs

@@ -0,0 +1,44 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2017-2022 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/>.
+
+//! Configuration of the networking layer.
+
+use std::{fmt, str};
+
+/// Name of a protocol, transmitted on the wire. Should be unique for each chain. Always UTF-8.
+#[derive(Clone, PartialEq, Eq, Hash)]
+pub struct ProtocolId(smallvec::SmallVec<[u8; 6]>);
+
+impl<'a> From<&'a str> for ProtocolId {
+	fn from(bytes: &'a str) -> ProtocolId {
+		Self(bytes.as_bytes().into())
+	}
+}
+
+impl AsRef<str> for ProtocolId {
+	fn as_ref(&self) -> &str {
+		str::from_utf8(&self.0[..])
+			.expect("the only way to build a ProtocolId is through a UTF-8 String; qed")
+	}
+}
+
+impl fmt::Debug for ProtocolId {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		fmt::Debug::fmt(self.as_ref(), f)
+	}
+}