Implement UUPS proxy (ERC1822) (#2542)

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

contracts/utils/README.adoc

@@ -96,4 +96,6 @@ Note that, in all cases, accounts simply _declare_ their interfaces, but they ar
 
 {{Strings}}
 
+{{StorageSlot}}
+
 {{Multicall}}

contracts/utils/StorageSlot.sol

@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+/**
+ * @dev Library for reading and writing primitive types to specific storage slots.
+ *
+ * Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.
+ * This library helps with reading and writing to such slots without the need for inline assembly.
+ *
+ * The functions in this library return Slot structs that contain a `value` member that can be used to read or write.
+ *
+ * Example usage to set ERC1967 implementation slot:
+ * ```
+ * contract ERC1967 {
+ *     bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
+ *
+ *     function _getImplementation() internal view returns (address) {
+ *         return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
+ *     }
+ *
+ *     function _setImplementation(address newImplementation) internal {
+ *         require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
+ *         StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
+ *     }
+ * }
+ * ```
+ *
+ * Available since v4.1.0 for `address`, `bool`, `bytes32`, and `uint256`.
+ */
+library StorageSlot {
+    struct AddressSlot {
+        address value;
+    }
+
+    struct BooleanSlot {
+        bool value;
+    }
+
+    struct Bytes32Slot {
+        bytes32 value;
+    }
+
+    struct Uint256Slot {
+        uint256 value;
+    }
+
+    /**
+     * @dev Returns an `AddressSlot` with member `value` located at `slot`.
+     */
+    function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
+        assembly {
+            r.slot := slot
+        }
+    }
+
+    /**
+     * @dev Returns an `BooleanSlot` with member `value` located at `slot`.
+     */
+    function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
+        assembly {
+            r.slot := slot
+        }
+    }
+
+    /**
+     * @dev Returns an `Bytes32Slot` with member `value` located at `slot`.
+     */
+    function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
+        assembly {
+            r.slot := slot
+        }
+    }
+
+    /**
+     * @dev Returns an `Uint256Slot` with member `value` located at `slot`.
+     */
+    function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
+        assembly {
+            r.slot := slot
+        }
+    }
+}