[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>

polkadot/xcm/xcm-builder/src/lib.rs

@@ -83,6 +83,9 @@ pub use weight::{
 	FixedRateOfFungible, FixedWeightBounds, TakeRevenue, UsingComponents, WeightInfoBounds,
 };
 
+mod matches_location;
+pub use matches_location::{StartsWith, StartsWithExplicitGlobalConsensus};
+
 mod matches_token;
 pub use matches_token::{IsAbstract, IsConcrete};
 
@@ -90,7 +93,7 @@ mod matcher;
 pub use matcher::{CreateMatcher, MatchXcm, Matcher};
 
 mod filter_asset_location;
-pub use filter_asset_location::{Case, NativeAsset};
+pub use filter_asset_location::{AllAssets, Case, LocationWithAssetFilters, NativeAsset};
 
 mod routing;
 pub use routing::{WithTopicSource, WithUniqueTopic};
@@ -99,7 +102,7 @@ mod universal_exports;
 pub use universal_exports::{
 	ensure_is_remote, BridgeBlobDispatcher, BridgeMessage, DispatchBlob, DispatchBlobError,
 	ExporterFor, HaulBlob, HaulBlobError, HaulBlobExporter, NetworkExportTable,
-	SovereignPaidRemoteExporter, UnpaidLocalExporter, UnpaidRemoteExporter,
+	NetworkExportTableItem, SovereignPaidRemoteExporter, UnpaidLocalExporter, UnpaidRemoteExporter,
 };
 
 mod origin_aliases;