Add Statemint as Combinations of (Location, Asset) pairs which Pendulum trust as reserves.

[RustNinja]

Need to add configuration of Combination of (Location, Asset) to pendulum xcm_config.rs

Reproduce step:
here is extrinsic for Stetemint to check reserve transfer assets for Statemint USDT to Pendulum chain.

encoded call data
0x1f0801010100b92001000101004e5d80a091a712b727ecbb00882bb28d4d64a6e7f6c87654b3243c489623f5100104000002043205011f0002093d000000000000

Here is the pendulum block details where xcmpQueue pallet emit Fail event with error UntrustedReserveLocation
error description

IsReserve is configuration for trustable chain as reserve chain for assets. link to polkadot repo

Now pendulum support only Native assets in xcm_executor config

https://github.com/pendulum-chain/pendulum/blob/main/runtime/pendulum/src/xcm_config.rs#L243

pub struct XcmConfig;
impl xcm_executor::Config for XcmConfig {
	...
	type IsReserve = NativeAsset;
	...
}

need update configuration to following:

/// A `FilterAssetLocation` implementation. Filters multi native assets whose
/// reserve is same with `origin`.
pub struct MultiNativeAsset<ReserveProvider>(PhantomData<ReserveProvider>);
impl<ReserveProvider> FilterAssetLocation for MultiNativeAsset<ReserveProvider>
where
	ReserveProvider: Reserve,
{
	fn filter_asset_location(asset: &MultiAsset, origin: &MultiLocation) -> bool {
		if let Some(ref reserve) = ReserveProvider::reserve(asset) {
			if reserve == origin {
				return true;
			}
		}
		false
	}
}

type IsReserve = MultiNativeAsset<RelativeReserveProvider>;