#890: Add ECDSA.toEthSignedMessageHash(bytes) for abritrary length message hashing (#2865)

* #890: Add ECDSA#toEthSignedMessage for bytes type

* refactor

* add test, refactor

* select overloaded function explicitly

* use short test message string

* add changelog entry

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>
Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>

contracts/utils/cryptography/ECDSA.sol

@@ -2,6 +2,8 @@
 
 pragma solidity ^0.8.0;
 
+import "../Strings.sol";
+
 /**
  * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
  *
@@ -204,6 +206,18 @@ library ECDSA {
         return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
     }
 
+    /**
+     * @dev Returns an Ethereum Signed Message, created from `s`. This
+     * produces hash corresponding to the one signed with the
+     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
+     * JSON-RPC method as part of EIP-191.
+     *
+     * See {recover}.
+     */
+    function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
+        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", Strings.toString(s.length), s));
+    }
+
     /**
      * @dev Returns an Ethereum Signed Typed Data, created from a
      * `domainSeparator` and a `structHash`. This produces hash corresponding