Treasury spends various asset kinds (#1333)

### Summary 

This PR introduces new dispatchables to the treasury pallet, allowing
spends of various asset types. The enhanced features of the treasury
pallet, in conjunction with the asset-rate pallet, are set up and
enabled for Westend and Rococo.

### Westend and Rococo runtimes.

Polkadot/Kusams/Rococo Treasury can accept proposals for `spends` of
various asset kinds by specifying the asset's location and ID.

#### Treasury Instance New Dispatchables:
- `spend(AssetKind, AssetBalance, Beneficiary, Option<ValidFrom>)` -
propose and approve a spend;
- `payout(SpendIndex)` - payout an approved spend or retry a failed
payout
- `check_payment(SpendIndex)` - check the status of a payout;
- `void_spend(SpendIndex)` - void previously approved spend;
> existing spend dispatchable renamed to spend_local

in this context, the `AssetKind` parameter contains the asset's location
and it's corresponding `asset_id`, for example:
`USDT` on `AssetHub`,
``` rust
location = MultiLocation(0, X1(Parachain(1000)))
asset_id = MultiLocation(0, X2(PalletInstance(50), GeneralIndex(1984)))
```

the `Beneficiary` parameter is a `MultiLocation` in the context of the
asset's location, for example
``` rust
// the Fellowship salary pallet's location / account
FellowshipSalaryPallet = MultiLocation(1, X2(Parachain(1001), PalletInstance(64)))
// or custom `AccountId`
Alice = MultiLocation(0, AccountId32(network: None, id: [1,...]))
```

the `AssetBalance` represents the amount of the `AssetKind` to be
transferred to the `Beneficiary`. For permission checks, the asset
amount is converted to the native amount and compared against the
maximum spendable amount determined by the commanding spend origin.

the `spend` dispatchable allows for batching spends with different
`ValidFrom` arguments, enabling milestone-based spending. If the
expectations tied to an approved spend are not met, it is possible to
void the spend later using the `void_spend` dispatchable.

Asset Rate Pallet provides the conversion rate from the `AssetKind` to
the native balance.

#### Asset Rate Instance Dispatchables:
- `create(AssetKind, Rate)` - initialize a conversion rate to the native
balance for the given asset
- `update(AssetKind, Rate)` - update the conversion rate to the native
balance for the given asset
- `remove(AssetKind)` - remove an existing conversion rate to the native
balance for the given asset

the pallet's dispatchables can be executed by the Root or Treasurer
origins.

### Treasury Pallet

Treasury Pallet can accept proposals for `spends` of various asset kinds
and pay them out through the implementation of the `Pay` trait.

New Dispatchables:
- `spend(Config::AssetKind, AssetBalance, Config::Beneficiary,
Option<ValidFrom>)` - propose and approve a spend;
- `payout(SpendIndex)` - payout an approved spend or retry a failed
payout;
- `check_payment(SpendIndex)` - check the status of a payout;
- `void_spend(SpendIndex)` - void previously approved spend;
> existing spend dispatchable renamed to spend_local

The parameters' types of the `spend` dispatchable exposed via the
pallet's `Config` and allows to propose and accept a spend of a certain
amount.

An approved spend can be claimed via the `payout` within the
`Config::SpendPeriod`. Clients provide an implementation of the `Pay`
trait which can pay an asset of the `AssetKind` to the `Beneficiary` in
`AssetBalance` units.

The implementation of the Pay trait might not have an immediate final
payment status, for example if implemented over `XCM` and the actual
transfer happens on a remote chain.

The `check_status` dispatchable can be executed to update the spend's
payment state and retry the `payout` if the payment has failed.

---------

Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>
Co-authored-by: command-bot <>

cumulus/parachains/integration-tests/emulated/assets/asset-hub-westend/Cargo.toml

@@ -18,17 +18,24 @@ frame-system = { path = "../../../../../../substrate/frame/system", default-feat
 pallet-balances = { path = "../../../../../../substrate/frame/balances", default-features = false}
 pallet-assets = { path = "../../../../../../substrate/frame/assets", default-features = false}
 pallet-asset-conversion = { path = "../../../../../../substrate/frame/asset-conversion", default-features = false}
+pallet-treasury = { path = "../../../../../../substrate/frame/treasury", default-features = false}
+pallet-asset-rate = { path = "../../../../../../substrate/frame/asset-rate", default-features = false}
 
 # Polkadot
 polkadot-core-primitives = { path = "../../../../../../polkadot/core-primitives", default-features = false}
 polkadot-parachain-primitives = { path = "../../../../../../polkadot/parachain", default-features = false}
+polkadot-runtime-common = { path = "../../../../../../polkadot/runtime/common" }
 polkadot-runtime-parachains = { path = "../../../../../../polkadot/runtime/parachains" }
 xcm = { package = "staging-xcm", path = "../../../../../../polkadot/xcm", default-features = false}
+xcm-builder = { package = "staging-xcm-builder",  path = "../../../../../../polkadot/xcm/xcm-builder", default-features = false}
+xcm-executor = { package = "staging-xcm-executor",  path = "../../../../../../polkadot/xcm/xcm-executor", default-features = false}
 pallet-xcm = { path = "../../../../../../polkadot/xcm/pallet-xcm", default-features = false}
 
 # Cumulus
 parachains-common = { path = "../../../../common" }
 asset-hub-westend-runtime = { path = "../../../../runtimes/assets/asset-hub-westend" }
+cumulus-pallet-dmp-queue = { default-features = false, path = "../../../../../pallets/dmp-queue" }
+cumulus-pallet-parachain-system = { default-features = false, path = "../../../../../pallets/parachain-system" }
 
 # Local
 xcm-emulator = { path = "../../../../../xcm/xcm-emulator", default-features = false}
@@ -37,15 +44,21 @@ integration-tests-common = { path = "../../common", default-features = false}
 [features]
 runtime-benchmarks = [
 	"asset-hub-westend-runtime/runtime-benchmarks",
+	"cumulus-pallet-parachain-system/runtime-benchmarks",
 	"frame-support/runtime-benchmarks",
 	"frame-system/runtime-benchmarks",
 	"integration-tests-common/runtime-benchmarks",
 	"pallet-asset-conversion/runtime-benchmarks",
+	"pallet-asset-rate/runtime-benchmarks",
 	"pallet-assets/runtime-benchmarks",
 	"pallet-balances/runtime-benchmarks",
+	"pallet-treasury/runtime-benchmarks",
 	"pallet-xcm/runtime-benchmarks",
 	"parachains-common/runtime-benchmarks",
 	"polkadot-parachain-primitives/runtime-benchmarks",
+	"polkadot-runtime-common/runtime-benchmarks",
 	"polkadot-runtime-parachains/runtime-benchmarks",
 	"sp-runtime/runtime-benchmarks",
+	"xcm-builder/runtime-benchmarks",
+	"xcm-executor/runtime-benchmarks",
 ]