feat: add SUSDS connectors

contracts/mainnet/connectors/susds/events.sol

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+//SPDX-License-Identifier: MIT
+pragma solidity ^0.8.2;
+
+contract Events {
+    event LogDeposit(
+        uint256 usdsAmount,
+        uint256 susdsAmount,
+        uint256 getId,
+        uint256 setId
+    );
+    event LogWithdraw(
+        uint256 susdsAmount,
+        uint256 usdsAmount,
+        uint256 getId,
+        uint256 setId
+    );
+}

contracts/mainnet/connectors/susds/helpers.sol

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+//SPDX-License-Identifier: MIT
+pragma solidity ^0.8.2;
+
+import {ISUSDS} from "./interfaces.sol";
+import {TokenInterface} from "../../common/interfaces.sol";
+
+contract Helpers {
+    /**
+     * @dev referral key
+     */
+    uint16 internal constant referralKey = 0;
+
+    /**
+     * @dev susds interface
+     */
+    ISUSDS internal constant susds =
+        ISUSDS(0xa3931d71877C0E7a3148CB7Eb4463524FEc27fbD);
+
+    /**
+     * @dev usds interface
+     */
+    TokenInterface internal constant usds =
+        TokenInterface(0xdC035D45d973E3EC169d2276DDab16f1e407384F);
+}

contracts/mainnet/connectors/susds/interfaces.sol

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+//SPDX-License-Identifier: MIT
+pragma solidity ^0.8.2;
+
+interface ISUSDS {
+    function approve(address, uint256) external;
+
+    function balanceOf(address) external view returns (uint256);
+
+    function deposit(
+        uint256 assets,
+        address receiver,
+        uint16 referral
+    ) external returns (uint256 shares);
+
+    function withdraw(
+        uint256 assets,
+        address receiver,
+        address owner
+    ) external returns (uint256 shares);
+}

contracts/mainnet/connectors/susds/main.sol

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+//SPDX-License-Identifier: MIT
+pragma solidity ^0.8.2;
+
+import {Helpers} from "./helpers.sol";
+import {Events} from "./events.sol";
+import {Basic} from "../../common/basic.sol";
+
+contract SUSDSConnector is Basic, Helpers, Events {
+     /**
+     * @dev Deposit USDS into sUSDS.
+     * @notice Deposit USDS into sUSDS (Saving USDS).
+     * @param usdsAmount The amount of USDS to deposit. (For max: `uint256(-1)`)
+     * @param getId ID to retrieve USDS amount.
+     * @param setId ID stores the amount of sUSDS.
+     */
+    function deposit(
+        uint256 usdsAmount,
+        uint256 getId,
+        uint256 setId
+    ) external returns (string memory _eventName, bytes memory _eventParam) {
+        uint256 _usdsAmount = getUint(getId, usdsAmount);
+        _usdsAmount = _usdsAmount == type(uint).max
+            ? usds.balanceOf(address(this))
+            : _usdsAmount;
+
+        // TODO: Obtain referral code
+        usds.approve(address(susds), _usdsAmount);
+        uint256 _susdsAmount = susds.deposit(_usdsAmount, address(this), 0); // this returns shares
+
+        setUint(setId, _susdsAmount);
+
+        _eventName = "LogDeposit(uint256,uint256,uint256,uint256)";
+        _eventParam = abi.encode(_usdsAmount, _susdsAmount, getId, setId);
+    }
+
+    /**
+     * @dev Withdraw sUSDS into USDS.
+     * @notice Withdraw sUSDS into USDS (Saving USDS).
+     * @param susdsAmount The amount of USDS to withdraw. (For max: `uint256(-1)`)
+     * @param getId ID to retrieve sUSDS amount.
+     * @param setId ID stores the amount of USDS.
+     */
+    function withdraw(
+        uint256 susdsAmount,
+        uint256 getId,
+        uint256 setId
+    ) external returns (string memory _eventName, bytes memory _eventParam) {
+        uint256 _susdsAmount = getUint(getId, susdsAmount);
+        _susdsAmount = _susdsAmount == type(uint).max
+            ? susds.balanceOf(address(this))
+            : _susdsAmount;
+
+        susds.approve(address(susds), _susdsAmount);
+        uint256 _usdsAmount = susds.withdraw(
+            _susdsAmount,
+            address(this),
+            address(this)
+        ); // this returns shares
+
+        setUint(setId, _usdsAmount);
+
+        _eventName = "LogWithdraw(uint256,uint256,uint256,uint256)";
+        _eventParam = abi.encode(_susdsAmount, _usdsAmount, getId, setId);
+    }
+}
+
+contract ConnectV2SUSDS is SUSDSConnector {
+    string public constant name = "SUSDS-v1.0";
+}