cumulus: add asset-hub-rococo runtime based on asset-hub-kusama and add asset-bridging support to it (#1215)

This commit adds Rococo Asset Hub dedicated runtime so we can test new
features here, before merging them in Kusama Asset Hub.
Also adds one such feature: asset transfer over bridge (Rococo AssetHub
<> Wococo AssetHub)

- clone `asset-hub-kusama-runtime` -> `asset-hub-rococo-runtime`
- make it use Rococo primitives, names, assets, constants, etc
- add asset-transfer-over-bridge support to Rococo AssetHub <> Wococo
AssetHub

Fixes #1128

---------

Co-authored-by: Branislav Kontur <bkontur@gmail.com>
Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>
Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>

cumulus/parachains/common/src/lib.rs

@@ -20,6 +20,7 @@ pub mod kusama;
 pub mod polkadot;
 pub mod rococo;
 pub mod westend;
+pub mod wococo;
 pub mod xcm_config;
 pub use constants::*;
 pub use opaque::*;

cumulus/parachains/common/src/wococo.rs

@@ -0,0 +1,17 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// re-export rococo
+pub use crate::rococo::{consensus, currency, fee};

cumulus/parachains/common/src/xcm_config.rs

@@ -14,7 +14,6 @@
 // limitations under the License.
 
 use crate::impls::AccountIdOf;
-use core::marker::PhantomData;
 use cumulus_primitives_core::{IsSystem, ParaId};
 use frame_support::{
 	traits::{fungibles::Inspect, tokens::ConversionToAssetBalance, ContainsPair},
@@ -22,6 +21,7 @@ use frame_support::{
 };
 use log;
 use sp_runtime::traits::Get;
+use sp_std::marker::PhantomData;
 use xcm::latest::prelude::*;
 
 /// A `ChargeFeeInFungibles` implementation that converts the output of