[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>

substrate/frame/support/src/traits.rs

@@ -34,7 +34,7 @@ mod members;
 #[allow(deprecated)]
 pub use members::{AllowAll, DenyAll, Filter};
 pub use members::{
-	AsContains, ChangeMembers, Contains, ContainsLengthBound, ContainsPair, Everything,
+	AsContains, ChangeMembers, Contains, ContainsLengthBound, ContainsPair, Equals, Everything,
 	EverythingBut, FromContainsPair, InitializeMembers, InsideBoth, IsInVec, Nothing,
 	RankedMembers, SortedMembers, TheseExcept,
 };