Add a double ended queue (#3153)

* add vector, lifo and fifo structures

* fix lint

* need more memory for coverage

* remove Vector wrappers and gas optimization

* refactor Vector testing

* revert package.json changes

* rename to DoubleEndedQueue

* rename and refactor

* refactor tests and expand coverage

* test for custom errors

* add changelog entry

* add docs

* add sample code and note about storage vs. memory

* add available since

* lint

* use underscore for struct members

* add struct documentation

* remove SafeCast in length

* rename i -> index and improve docs

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

contracts/mocks/DoubleEndedQueueMock.sol

@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "../utils/structs/DoubleEndedQueue.sol";
+
+// Bytes32Deque
+contract Bytes32DequeMock {
+    using DoubleEndedQueue for DoubleEndedQueue.Bytes32Deque;
+
+    event OperationResult(bytes32 value);
+
+    DoubleEndedQueue.Bytes32Deque private _vector;
+
+    function pushBack(bytes32 value) public {
+        _vector.pushBack(value);
+    }
+
+    function pushFront(bytes32 value) public {
+        _vector.pushFront(value);
+    }
+
+    function popFront() public returns (bytes32) {
+        bytes32 value = _vector.popFront();
+        emit OperationResult(value);
+        return value;
+    }
+
+    function popBack() public returns (bytes32) {
+        bytes32 value = _vector.popBack();
+        emit OperationResult(value);
+        return value;
+    }
+
+    function front() public view returns (bytes32) {
+        return _vector.front();
+    }
+
+    function back() public view returns (bytes32) {
+        return _vector.back();
+    }
+
+    function at(uint256 i) public view returns (bytes32) {
+        return _vector.at(i);
+    }
+
+    function clear() public {
+        _vector.clear();
+    }
+
+    function length() public view returns (uint256) {
+        return _vector.length();
+    }
+
+    function empty() public view returns (bool) {
+        return _vector.empty();
+    }
+}