Query account balances using accounts_common

[valentinfernandez1]

Adds the query_account_balance functionality as suggested in issue #199 using the crate accounts_common from cumulus. this allows to query multiple balances from an account with a single runtime api call.

        impl assets_common::runtime_api::FungiblesApi<
		Block,
		AccountId,
	> for Runtime
	{
		fn query_account_balances(account: AccountId) -> Result<Vec<MultiAsset>, assets_common::runtime_api::FungiblesAccessError> {
			use assets_common::fungible_conversion::{convert, convert_balance};
			Ok([
				// collect pallet_balance
				{
					let balance = Balances::free_balance(account.clone());
					if balance > 0 {
						vec![convert_balance::<RelayLocation, Balance>(balance)?]
					} else {
						vec![]
					}
				},
				// collect pallet_assets (TrustBackedAssets)
				convert::<_, _, _, _, TrustBackedAssetsConvertedConcreteId>(
					Assets::account_balances(account.clone())
						.iter()
						.filter(|(_, balance)| balance > &0)
				)?
			].concat().into())
		}
	}

Also the Converter TrustBackedAssetsConvertedConcreteId was added

---

Inside trappist/xcm_config.rs LocalFungiblesTransactor was modified including this new Assetconverter from:

/// Means for transacting assets besides the native currency on this chain.
pub type LocalFungiblesTransactor = FungiblesAdapter<
	.....
	// Use this currency when it is a fungible asset matching the given location or name:
	ConvertedConcreteId<
		AssetIdForTrustBackedAssets,
		Balance,
		AsPrefixedGeneralIndex<AssetsPalletLocation, AssetIdForTrustBackedAssets, JustTry>,
		JustTry,
	>,
	....
>;

to:

/// Means for transacting assets besides the native currency on this chain.
pub type LocalFungiblesTransactor = FungiblesAdapter<
	.....
	// Use this currency when it is a fungible asset matching the given location or name:
	TrustBackedAssetsConvertedConcreteId,
	....
>;

Since this accomplishes the same thing and this converter will probably be needed for #169.

[valentinfernandez1]

In addition to this i have noticed that the assets-common, contains a more interesting MultiAssetConverter/convert_ref implementation that the one we have in our xcm-primitives.

I see a couple of improvements in the asset-common as:

• Better error management.
• It returns the amount in addition to the asset id.

This should also be considered in the asset-registry pallet that we are implementing.

Also this needs to be implemented but I still have doubts about this:

i see a period of time where both XCM primitives will cohexist until the xcm-primitives is removed or replaced.

[hbulgarini]

In addition to this i have noticed that the assets-common, contains a more interesting MultiAssetConverter/convert_ref implementation that the one we have in our xcm-primitives.
I see a couple of improvements in the asset-common as:

• Better error management.
• It returns the amount in addition to the asset id.

This should also be considered in the asset-registry pallet that we are implementing.

Also this needs to be implemented but I still have doubts about this:

i see a period of time where both XCM primitives will cohexist until the xcm-primitives is removed or replaced.

#199 (comment)

[valentinfernandez1]

I would resolve the convert_ref implementation and how it should be changed inside the asset_registry in a different PR. Let's discuss it in the sync meeting.