Add EVM Contracts (#637)

* add contracts

* add ens

* update erc721

* Add AssetsBridgeErc20 contracts

* Add ens contracts

* Add chainx mainnet

* remove notes

Co-authored-by: NingBo Wang <2536935847@qq.com>
Co-authored-by: icodezjb <icodezjb@users.noreply.github.com>

contracts/AssetsBridgeAdaptor.sol

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.4.1/contracts/utils/Context.sol";
+import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.4.1/contracts/access/Ownable.sol";
+
+/**
+ * @dev Interface of the SherpaX AssetsBridge
+ */
+interface IAssetsBridge {
+    /*
+     * @dev mint the token to account for assets bridge admin.
+     * @param account The receiver of token.
+     * @param amount The amount of token.
+     */
+    function mint_into(address account, uint256 amount) external returns (bool);
+
+    /*
+     * @dev burn the token from account for assets bridge admin.
+     * @param account The owner of token.
+     * @param amount The amount of token.
+     */
+    function burn_from(address account, uint256 amount) external returns (bool);
+}
+
+abstract contract AssetsBridgeAdmin is Context {
+    address public constant admin = 0x1111111111111111111111111111111111111111;
+
+    modifier AssetsBridgeRequire() {
+        require(_msgSender() == admin, "AssetsBridge: require called by the assets bridge admin address");
+
+        _;
+    }
+}
+
+abstract contract AssetsBridgeOwner is Context, Ownable {
+    modifier AssetsBridgeRequire() {
+        require(_msgSender() == owner(), "AssetsBridge: require called by owner");
+
+        _;
+    }
+}
+
+abstract contract AssetsBridgeAdminOrOwner is Context, Ownable {
+    address public constant admin = 0x1111111111111111111111111111111111111111;
+
+    modifier AssetsBridgeRequire() {
+        require(_msgSender() == owner() || _msgSender() == admin, "AssetsBridge: require called by owner or admin");
+
+        _;
+    }
+}