Ability to capture trees as JSON files (#1565)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1565

This adds a `captureTree` method intended to be injected in somewhere where you would like a JSON representation of a yoga tree. Right now it is very simple and just calls on `nodeToString` to serialize a node into JSON, and then saves that into a file in the given path. Some buck file changes needed to be done as well to use this in other files.

Reviewed By: NickGerleman

Differential Revision: D52972995

fbshipit-source-id: f4e09a815edef92ab959cfc76bacccbce225d940

capture/CaptureTree.cpp

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <fstream>
+
+#include <capture/CaptureTree.h>
+#include <capture/NodeToString.h>
+
+namespace facebook::yoga {
+
+void captureTree(YGNodeRef node, const std::filesystem::path& path) {
+  std::string str;
+  nodeToString(str, node, YGPrintOptionsStyle | YGPrintOptionsChildren);
+  std::ofstream file(path);
+  file << str;
+}
+
+} // namespace facebook::yoga

capture/CaptureTree.h

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <filesystem>
+
+#include <yoga/Yoga.h>
+
+namespace facebook::yoga {
+
+void captureTree(YGNodeRef node, const std::filesystem::path& path);
+
+} // namespace facebook::yoga