Fix xcm reserve transfer from Rockmine <> Trappist.

[hbulgarini]

This PR fixes the reserve transfer asset from Rockmine to Trappist.

It adds the following Trader tuple:

pub type Trader = (
	FixedRateOfFungible<RUsdPerSecond, ()>,
	FixedRateOfFungible<RocPerSecond, ()>,
	UsingComponents<WeightToFee, SelfReserve, AccountId, Balances, ToAuthor<Runtime>>,
);

As you can see, also Rocs can be computed as a reference value of 1 ROC = 7 RUSD"

	pub RUsdPerSecond: (xcm::v1::AssetId, u128) = (
		MultiLocation::new(1, X3(Parachain(1000), PalletInstance(50), GeneralIndex(1984))).into(),
		default_fee_per_second() * 10
	);
	/// Roc = 7 RUSD
	pub RocPerSecond: (AssetId, u128) = (MultiLocation::parent().into(), default_fee_per_second() * 70);

Also there was an issue with the pallet-xcm-benchmarking that was setting the weight for reserve_asset_deposited to u64::MAX. I suspect this is a hack for CGP to avoid reserve based transfers from other reserves.

[stiiifff]

@hbulgarini Re. the FixedRateOfFungible for Roc, does this mean we need to allow teleports ? Or create a derived asset and add it to the Asset Registry ?

[hbulgarini]

@hbulgarini Re. the FixedRateOfFungible for Roc, does this mean we need to allow teleports ? Or create a derived asset and add it to the Asset Registry ?

Create a derived asset and add it to the asset registry