[testnet] Add AssetHubRococo <-> AssetHubWestend asset bridging support (#1967)

## Summary

Asset bridging support for AssetHub**Rococo** <-> AssetHub**Wococo** was
added [here](https://github.com/paritytech/polkadot-sdk/pull/1215), so
now we aim to bridge AssetHub**Rococo** and AssetHub**Westend**. (And
perhaps retire AssetHubWococo and the Wococo chains).

## Solution

**bridge-hub-westend-runtime**
- added new runtime as a copy of `bridge-hub-rococo-runtime`
- added support for bridging to `BridgeHubRococo`
- added tests and benchmarks

**bridge-hub-rococo-runtime**
- added support for bridging to `BridgeHubWestend`
- added tests and benchmarks
- internal refactoring by splitting bridge configuration per network,
e.g., `bridge_to_whatevernetwork_config.rs`.

**asset-hub-rococo-runtime**
- added support for asset bridging to `AssetHubWestend` (allows to
receive only WNDs)
- added new xcm router for `Westend`
- added tests and benchmarks

**asset-hub-westend-runtime**
- added support for asset bridging to `AssetHubRococo` (allows to
receive only ROCs)
- added new xcm router for `Rococo`
- added tests and benchmarks

## Deployment

All changes will be deployed as a part of
https://github.com/paritytech/polkadot-sdk/issues/1988.

## TODO

- [x] benchmarks for all pallet instances
- [x] integration tests
- [x] local run scripts


Relates to:
https://github.com/paritytech/parity-bridges-common/issues/2602
Relates to: https://github.com/paritytech/polkadot-sdk/issues/1988

---------

Co-authored-by: command-bot <>
Co-authored-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>

bridges/primitives/chain-westend/src/lib.rs

@@ -0,0 +1,79 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common 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.
+
+// Parity Bridges Common 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 Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+// RuntimeApi generated functions
+#![allow(clippy::too_many_arguments)]
+
+pub use bp_polkadot_core::*;
+
+use bp_header_chain::ChainWithGrandpa;
+use bp_runtime::{decl_bridge_finality_runtime_apis, Chain};
+use frame_support::{parameter_types, weights::Weight};
+
+/// Westend Chain
+pub struct Westend;
+
+impl Chain for Westend {
+	type BlockNumber = <PolkadotLike as Chain>::BlockNumber;
+	type Hash = <PolkadotLike as Chain>::Hash;
+	type Hasher = <PolkadotLike as Chain>::Hasher;
+	type Header = <PolkadotLike as Chain>::Header;
+
+	type AccountId = <PolkadotLike as Chain>::AccountId;
+	type Balance = <PolkadotLike as Chain>::Balance;
+	type Nonce = <PolkadotLike as Chain>::Nonce;
+	type Signature = <PolkadotLike as Chain>::Signature;
+
+	fn max_extrinsic_size() -> u32 {
+		PolkadotLike::max_extrinsic_size()
+	}
+
+	fn max_extrinsic_weight() -> Weight {
+		PolkadotLike::max_extrinsic_weight()
+	}
+}
+
+impl ChainWithGrandpa for Westend {
+	const WITH_CHAIN_GRANDPA_PALLET_NAME: &'static str = WITH_WESTEND_GRANDPA_PALLET_NAME;
+	const MAX_AUTHORITIES_COUNT: u32 = MAX_AUTHORITIES_COUNT;
+	const REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY: u32 =
+		REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY;
+	const MAX_HEADER_SIZE: u32 = MAX_HEADER_SIZE;
+	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = AVERAGE_HEADER_SIZE_IN_JUSTIFICATION;
+}
+
+parameter_types! {
+	pub const SS58Prefix: u8 = 42;
+}
+
+// The SignedExtension used by Westend.
+pub use bp_polkadot_core::CommonSignedExtension as SignedExtension;
+
+/// Name of the parachains pallet in the Rococo runtime.
+pub const PARAS_PALLET_NAME: &str = "Paras";
+
+/// Name of the With-Westend GRANDPA pallet instance that is deployed at bridged chains.
+pub const WITH_WESTEND_GRANDPA_PALLET_NAME: &str = "BridgeWestendGrandpa";
+
+/// Maximal size of encoded `bp_parachains::ParaStoredHeaderData` structure among all Westend
+/// parachains.
+///
+/// It includes the block number and state root, so it shall be near 40 bytes, but let's have some
+/// reserve.
+pub const MAX_NESTED_PARACHAIN_HEAD_DATA_SIZE: u32 = 128;
+
+decl_bridge_finality_runtime_apis!(westend, grandpa);