Add missing documentation contract (#62)

Author: ernestognw

contracts/mocks/docs/utils/cryptography/ERC7739SignerECDSA.sol

@@ -0,0 +1,24 @@
+// contracts/ERC7739SignerECDSA.sol
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+import {ECDSA} from "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
+import {EIP712} from "@openzeppelin/contracts/utils/cryptography/EIP712.sol";
+
+import {ERC7739Signer} from "../../../../utils/cryptography/ERC7739Signer.sol";
+
+contract ERC7739SignerECDSA is ERC7739Signer {
+    address private immutable _signer;
+
+    constructor(address signerAddr) EIP712("ERC7739SignerECDSA", "1") {
+        _signer = signerAddr;
+    }
+
+    function _rawSignatureValidation(
+        bytes32 hash,
+        bytes calldata signature
+    ) internal view virtual override returns (bool) {
+        (address recovered, ECDSA.RecoverError err, ) = ECDSA.tryRecover(hash, signature);
+        return _signer == recovered && err == ECDSA.RecoverError.NoError;
+    }
+}