[XCMv5]Remove XCM testnet NetworkIds (#5390)

# Context
Close #5241, for more detail, please refer to
[RFC0108](polkadot-fellows/RFCs#108)
# Changes
- Remove `Rococo` and `Westend` from `NetworkId`
* Add `Rococo Genesis Hash` and `Westend Genesis Hash`

---------

Co-authored-by: Nazar Mokrynskyi <[email protected]>
Co-authored-by: Bastian Köcher <[email protected]>
Co-authored-by: Shawn Tabrizi <[email protected]>
Co-authored-by: Adrian Catangiu <[email protected]>
Co-authored-by: Francisco Aguirre <[email protected]>

bridges/snowbridge/pallets/system/src/mock.rs

@@ -18,7 +18,7 @@ use sp_runtime::{
 	traits::{AccountIdConversion, BlakeTwo256, IdentityLookup, Keccak256},
 	AccountId32, BuildStorage, FixedU128,
 };
-use xcm::prelude::*;
+use xcm::{latest::ROCOCO_GENESIS_HASH, prelude::*};
 
 #[cfg(feature = "runtime-benchmarks")]
 use crate::BenchmarkHelper;