Add a BitMap struct (#2710)

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

contracts/mocks/BitmapMock.sol

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "../utils/structs/BitMaps.sol";
+
+contract BitMapMock {
+    using BitMaps for BitMaps.BitMap;
+
+    BitMaps.BitMap private _bitmap;
+
+    function get(uint256 index) public view returns (bool) {
+        return _bitmap.get(index);
+    }
+
+    function setTo(uint256 index, bool value) public {
+        _bitmap.setTo(index, value);
+    }
+
+    function set(uint256 index) public {
+        _bitmap.set(index);
+    }
+
+    function unset(uint256 index) public {
+        _bitmap.unset(index);
+    }
+}