[xcm] Small enhancements for NetworkExportTable and xcm-builder (#1848)

## Summary

This PR introduces several enhancements.

The current implementation of `NetworkExportTable` lacks remote location
filtering support beyond `NetworkId` lookup. To provide more control and
granularity, it's essential to allow configuration for bridging to
different consensus `NetworkId` while restricting access e.g. to
particular remote parachains.

Additionally, the `StartsWith` and `Equals` and
`StartsWithExplicitGlobalConsensus` helper functions, which are in
active use, are moved to the `xcm-builder` and `frame_support` modules
for better code organization.

Adds a new `LocationWithAssetFilters` filter to enable location-based
and asset-related filtering. This filter is useful for configuring the
`pallet_xcm` filter for
[XcmTeleportFilter](https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/xcm/pallet-xcm/src/lib.rs#L212)
and
[XcmReserveTransferFilter](https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/xcm/pallet-xcm/src/lib.rs#L216)
to restrict specific assets.

Furthermore, the `BridgeMessage` fields are not accessible outside of
`xcm-builder`, limiting the ability to create custom logic dependent on
it.

---------

Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>

cumulus/parachains/runtimes/assets/common/src/lib.rs

@@ -21,11 +21,11 @@ pub mod local_and_foreign_assets;
 pub mod matching;
 pub mod runtime_api;
 
-use crate::matching::{Equals, LocalMultiLocationPattern, ParentLocation, StartsWith};
-use frame_support::traits::EverythingBut;
+use crate::matching::{LocalMultiLocationPattern, ParentLocation};
+use frame_support::traits::{Equals, EverythingBut};
 use parachains_common::AssetIdForTrustBackedAssets;
 use xcm::prelude::MultiLocation;
-use xcm_builder::{AsPrefixedGeneralIndex, MatchedConvertedConcreteId};
+use xcm_builder::{AsPrefixedGeneralIndex, MatchedConvertedConcreteId, StartsWith};
 use xcm_executor::traits::{Identity, JustTry};
 
 /// `MultiLocation` vs `AssetIdForTrustBackedAssets` converter for `TrustBackedAssets`
@@ -96,9 +96,9 @@ pub type PoolAssetsConvertedConcreteId<PoolAssetsPalletLocation, Balance> =
 #[cfg(test)]
 mod tests {
 	use super::*;
-	use crate::matching::StartsWithExplicitGlobalConsensus;
 	use sp_runtime::traits::MaybeEquivalence;
 	use xcm::latest::prelude::*;
+	use xcm_builder::StartsWithExplicitGlobalConsensus;
 	use xcm_executor::traits::{Error as MatchError, MatchesFungibles};
 
 	#[test]

cumulus/parachains/runtimes/assets/common/src/local_and_foreign_assets.rs

@@ -407,13 +407,14 @@ where
 #[cfg(test)]
 mod tests {
 	use crate::{
-		local_and_foreign_assets::MultiLocationConverter, matching::StartsWith,
-		AssetIdForPoolAssetsConvert, AssetIdForTrustBackedAssetsConvert,
+		local_and_foreign_assets::MultiLocationConverter, AssetIdForPoolAssetsConvert,
+		AssetIdForTrustBackedAssetsConvert,
 	};
 	use frame_support::traits::EverythingBut;
 	use pallet_asset_conversion::{MultiAssetIdConversionResult, MultiAssetIdConverter};
 	use sp_runtime::traits::MaybeEquivalence;
 	use xcm::latest::prelude::*;
+	use xcm_builder::StartsWith;
 
 	#[test]
 	fn test_multi_location_converter_works() {

cumulus/parachains/runtimes/assets/common/src/matching.rs

@@ -14,38 +14,12 @@
 // limitations under the License.
 
 use cumulus_primitives_core::ParaId;
-use frame_support::{
-	pallet_prelude::Get,
-	traits::{Contains, ContainsPair},
-};
+use frame_support::{pallet_prelude::Get, traits::ContainsPair};
 use xcm::{
 	latest::prelude::{MultiAsset, MultiLocation},
 	prelude::*,
 };
 
-pub struct StartsWith<T>(sp_std::marker::PhantomData<T>);
-impl<Location: Get<MultiLocation>> Contains<MultiLocation> for StartsWith<Location> {
-	fn contains(t: &MultiLocation) -> bool {
-		t.starts_with(&Location::get())
-	}
-}
-
-pub struct Equals<T>(sp_std::marker::PhantomData<T>);
-impl<Location: Get<MultiLocation>> Contains<MultiLocation> for Equals<Location> {
-	fn contains(t: &MultiLocation) -> bool {
-		t == &Location::get()
-	}
-}
-
-pub struct StartsWithExplicitGlobalConsensus<T>(sp_std::marker::PhantomData<T>);
-impl<Network: Get<NetworkId>> Contains<MultiLocation>
-	for StartsWithExplicitGlobalConsensus<Network>
-{
-	fn contains(t: &MultiLocation) -> bool {
-		matches!(t.interior.global_consensus(), Ok(requested_network) if requested_network.eq(&Network::get()))
-	}
-}
-
 frame_support::parameter_types! {
 	pub LocalMultiLocationPattern: MultiLocation = MultiLocation::new(0, Here);
 	pub ParentLocation: MultiLocation = MultiLocation::parent();