Add Account framework (#5657)

contracts/interfaces/IERC7821.sol

@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+/**
+ * @dev Interface for minimal batch executor.
+ */
+interface IERC7821 {
+    /**
+     * @dev Executes the calls in `executionData`.
+     * Reverts and bubbles up error if any call fails.
+     *
+     * `executionData` encoding:
+     * - If `opData` is empty, `executionData` is simply `abi.encode(calls)`.
+     * - Else, `executionData` is `abi.encode(calls, opData)`.
+     *   See: https://eips.ethereum.org/EIPS/eip-7579
+     *
+     * Supported modes:
+     * - `bytes32(0x01000000000000000000...)`: does not support optional `opData`.
+     * - `bytes32(0x01000000000078210001...)`: supports optional `opData`.
+     *
+     * Authorization checks:
+     * - If `opData` is empty, the implementation SHOULD require that
+     *   `msg.sender == address(this)`.
+     * - If `opData` is not empty, the implementation SHOULD use the signature
+     *   encoded in `opData` to determine if the caller can perform the execution.
+     *
+     * `opData` may be used to store additional data for authentication,
+     * paymaster data, gas limits, etc.
+     *
+     * For calldata compression efficiency, if a Call.to is `address(0)`,
+     * it will be replaced with `address(this)`.
+     */
+    function execute(bytes32 mode, bytes calldata executionData) external payable;
+
+    /**
+     * @dev This function is provided for frontends to detect support.
+     * Only returns true for:
+     * - `bytes32(0x01000000000000000000...)`: does not support optional `opData`.
+     * - `bytes32(0x01000000000078210001...)`: supports optional `opData`.
+     */
+    function supportsExecutionMode(bytes32 mode) external view returns (bool);
+}