AK: Add RecursionDecision

Similar to IterationDecision, this can be returned from callbacks passed
to recursive traversal functions to signal how to proceed.

AK/RecursionDecision.h

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+namespace AK {
+
+enum class RecursionDecision {
+    Recurse,
+    Continue,
+    Break,
+};
+
+}
+
+using AK::RecursionDecision;