Add ERC20 and ERC777 fixed supply presets #2377 (#2399)

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

contracts/presets/ERC20PresetFixedSupply.sol

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.6.2;
+
+import "../token/ERC20/ERC20Burnable.sol";
+
+/**
+ * @dev {ERC20} token, including:
+ *
+ *  - Preminted initial supply
+ *  - Ability for holders to burn (destroy) their tokens
+ *  - No access control mechanism (for minting/pausing) and hence no governance
+ *
+ * This contract uses {ERC20Burnable} to include burn capabilities - head to
+ * its documentation for details.
+ */
+contract ERC20PresetFixedSupply is ERC20Burnable {
+    /**
+     * @dev Mints `initialSupply` amount of token and transfers them to `owner`.  
+     *
+     * See {ERC20-constructor}.
+     */
+    constructor(
+        string memory name,
+        string memory symbol,
+        uint256 initialSupply,
+        address owner
+    ) public ERC20(name, symbol) {
+        _mint(owner, initialSupply);
+    }
+}

contracts/presets/ERC777PresetFixedSupply.sol

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.6.2;
+
+import "../token/ERC777/ERC777.sol";
+
+/**
+ * @dev {ERC777} token, including:
+ *
+ *  - Preminted initial supply
+ *  - No access control mechanism (for minting/pausing) and hence no governance
+ */
+contract ERC777PresetFixedSupply is ERC777 {
+    /**
+     * @dev Mints `initialSupply` amount of token and transfers them to `owner`.  
+     *
+     * See {ERC777-constructor}.
+     */
+    constructor(
+        string memory name,
+        string memory symbol,
+        address[] memory defaultOperators,
+        uint256 initialSupply,
+        address owner
+    ) public ERC777(name, symbol, defaultOperators) {
+        _mint(owner, initialSupply, "", "");
+    }
+}

contracts/presets/README.adoc

@@ -16,3 +16,7 @@ TIP: Intermediate and advanced users can use these as starting points when writi
 {{ERC721PresetMinterPauserAutoId}}
 
 {{ERC1155PresetMinterPauser}}
+
+{{ERC20PresetFixedSupply}}
+
+{{ERC777PresetFixedSupply}}