connectors: Wrapped token lookup

[NunoAlexandre]

Part 2/2 of #1350

• Connector-wrapped tokens should have a AssetMetadata.location that encapsulates the EVM chain id and the specific EVM address of said token

  • We, therefore, can implement a lookup for Connector-wrapped assets that knows how to lookup that data from the asset's location

Changes

• Add ConnectorsWrappedToken, an enum type representing the Connectors Wrapped tokens we handle. At this moment, that's only EVM tokens. As described in the docs of that type, in the future it might be others such as Cosmos or Avalanche.

• We implement conversion between ConnectorsWrappedToken and MultiLocation

Usage

• When registering a ConnectorsWrappedToken in the OrmlAssetRegistry, we define the Metadata.location as ConnectorsWrappedTokenConvert<ConnectorsPalletIndex>>::convert(connectors_wrapped_token);

• In the connectors pallet we add a new type:

ConnectorsWrappedTokenConvert: Convert<ConnectorsWrappedToken, MultiLocation> + Convert<MultiLocation, Result<ConnectorsWrappedToken, ()>

• In the add_currency extrinsic of the connectors pallet, we will roughly do:

fn add_currency(currency_id: T::CurrencyId, domain: Domain) {
	let meta = T::AssetRegistry::metadata(currency_id).ok_or(Error::CurrencyMetadataNotFound)?;

	ensure!(
		meta.additional.transferability.includes_connectors(),
		Error::NotConnectorsTransferable
	);
	let wrapped_token = ConnectorsWrappedTokenConvert::convert(meta.location)
		.map_err(Error::NotConnectorsWrappedToken)?;

	match wrapped_token {
		ConnectorsWrappedToken::EVM { chain_id, address } => ensure!(
			chain_id == domain.chain_id,
			Error::DifferentWrappedTokenAndDomain
		),
	}

	// send the message
}

[wischli]

Overall LGTM. Added my two cents on the asset registry question and I feel like we are missing at least a Moonbeam derivation?

[mustermeiszer]

Looks good. Just wanted to highlight that we could imlement this purely on the connectors level without moving to the runtime level if we drop the pallet instance. But no blocker.