Add Dex pallet (#407)

* Move pallet-asset-conversion

* update licensing

* initial integration

* Integrate Currency & Assets types

* integrate liquidity tokens

* fmt

* integrate dex pallet tests

* fmt

* compilation error fixes

* integrate dex benchmarks

* fmt

* cargo clippy

* replace all occurrences of "asset" with "coin"

* add the actual add liq/swap logic to in-instructions

* add client side & tests

* fix deny

* Lint and changes

- Renames InInstruction::AddLiquidity to InInstruction::SwapAndAddLiquidity
- Makes create_pool an internal function
- Makes dex-pallet exclusively create pools against a native coin
- Removes various fees
- Adds new crates to GH workflow

* Fix rebase artifacts

* Correct other rebase artifact

* Correct CI specification for liquidity-tokens

* Correct primitives' test to the standardized pallet account scheme

---------

Co-authored-by: Luke Parker <lukeparker5132@gmail.com>

substrate/dex/pallet/src/mock.rs

@@ -0,0 +1,155 @@
+// This file was originally:
+
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// It has been forked into a crate distributed under the AGPL 3.0.
+// Please check the current distribution for up-to-date copyright and licensing information.
+
+//! Test environment for Dex pallet.
+
+use super::*;
+use crate as dex;
+
+use frame_support::{
+  construct_runtime,
+  traits::{ConstU32, ConstU64},
+};
+
+use sp_core::{H256, sr25519::Public};
+use sp_runtime::{
+  traits::{BlakeTwo256, IdentityLookup},
+  BuildStorage,
+};
+
+use serai_primitives::{Coin, Balance, Amount, system_address};
+
+pub use coins_pallet as coins;
+pub use liquidity_tokens_pallet as liquidity_tokens;
+
+type Block = frame_system::mocking::MockBlock<Test>;
+
+construct_runtime!(
+  pub enum Test
+  {
+    System: frame_system,
+    CoinsPallet: coins,
+    LiquidityTokens: liquidity_tokens,
+    Dex: dex,
+  }
+);
+
+impl frame_system::Config for Test {
+  type BaseCallFilter = frame_support::traits::Everything;
+  type BlockWeights = ();
+  type BlockLength = ();
+  type RuntimeOrigin = RuntimeOrigin;
+  type RuntimeCall = RuntimeCall;
+  type Nonce = u64;
+  type Hash = H256;
+  type Hashing = BlakeTwo256;
+  type AccountId = Public;
+  type Lookup = IdentityLookup<Self::AccountId>;
+  type Block = Block;
+  type RuntimeEvent = RuntimeEvent;
+  type BlockHashCount = ConstU64<250>;
+  type DbWeight = ();
+  type Version = ();
+  type PalletInfo = PalletInfo;
+  type AccountData = ();
+  type OnNewAccount = ();
+  type OnKilledAccount = ();
+  type SystemWeightInfo = ();
+  type SS58Prefix = ();
+  type OnSetCode = ();
+  type MaxConsumers = ConstU32<16>;
+}
+
+impl coins::Config for Test {
+  type RuntimeEvent = RuntimeEvent;
+}
+
+impl liquidity_tokens::Config for Test {
+  type RuntimeEvent = RuntimeEvent;
+}
+
+pub struct CoinConverter;
+impl MultiCoinIdConverter<Coin, Coin> for CoinConverter {
+  /// Returns the MultiCoinId representing the native currency of the chain.
+  fn get_native() -> Coin {
+    Coin::Serai
+  }
+
+  /// Returns true if the given MultiCoinId is the native currency.
+  fn is_native(coin: &Coin) -> bool {
+    coin.is_native()
+  }
+
+  /// If it's not native, returns the CoinId for the given MultiCoinId.
+  fn try_convert(coin: &Coin) -> MultiCoinIdConversionResult<Coin, Coin> {
+    if coin.is_native() {
+      MultiCoinIdConversionResult::Native
+    } else {
+      MultiCoinIdConversionResult::Converted(*coin)
+    }
+  }
+}
+
+impl Config for Test {
+  type RuntimeEvent = RuntimeEvent;
+  type Currency = CoinsPallet;
+  type CoinBalance = u64;
+  type CoinId = Coin;
+  type PoolCoinId = u32;
+  type Coins = CoinsPallet;
+  type PoolCoins = LiquidityTokens;
+  type WeightInfo = ();
+  type LPFee = ConstU32<3>; // means 0.3%
+  type MaxSwapPathLength = ConstU32<4>;
+  // 100 is good enough when the main currency has 12 decimals.
+  type MintMinLiquidity = ConstU64<100>;
+
+  type Balance = u64;
+  type HigherPrecisionBalance = u128;
+
+  type MultiCoinId = Coin;
+  type MultiCoinIdConverter = CoinConverter;
+
+  #[cfg(feature = "runtime-benchmarks")]
+  type BenchmarkHelper = ();
+}
+
+pub(crate) fn new_test_ext() -> sp_io::TestExternalities {
+  let mut t = frame_system::GenesisConfig::<Test>::default().build_storage().unwrap();
+
+  let accounts: Vec<Public> = vec![
+    system_address(b"account1").into(),
+    system_address(b"account2").into(),
+    system_address(b"account3").into(),
+    system_address(b"account4").into(),
+  ];
+  coins::GenesisConfig::<Test> {
+    accounts: accounts
+      .into_iter()
+      .map(|a| (a, Balance { coin: Coin::Serai, amount: Amount(1 << 60) }))
+      .collect(),
+  }
+  .assimilate_storage(&mut t)
+  .unwrap();
+
+  let mut ext = sp_io::TestExternalities::new(t);
+  ext.execute_with(|| System::set_block_number(1));
+  ext
+}