Stamp React Native Version Into C++ Code (facebook#28036)

Summary:
The PlatformConstants native module exposes the ability to query the React
Native version used to build native code. This is managed on iOS and Android by
a version bumping script, which replaces module code based on a template.

It is currently difficult to accurately determine this version for out-of-tree C++
platforms (I.e. React Native Windows). The version of upstream react-native we resolve to is ultimately
dependent on the version of react-native chosen a peer dependency, which is not
neccesarily constant given a build of react-native-windows.

We could try to hack around this, and make our native build try to reason about
the resolved pacakge for react-native using a lockfile, but a much cleaner
solution is to embed version into C++ code, similar to what is done for Android
and iOS. This change does that, adding a header with React Native version and
updating the build stamping script to write to it.

Usage sample:

```c++
  constants["reactNativeVersion"] = folly::dynamic::object();
  constants["reactNativeVersion"]["major"] = ReactNativeVersion.Major;
  constants["reactNativeVersion"]["minor"] = ReactNativeVersion.Minor;
  constants["reactNativeVersion"]["patch"] = ReactNativeVersion.Patch;
```
## Changelog

[General] [Added] - Stamp React Native Version Into C++ Code
Pull Request resolved: facebook#28036

Test Plan: Validated that the bumping script will accurately update the header, can compile under both MSVC and Clang.

Differential Revision: D19865992

Pulled By: hramos

fbshipit-source-id: 9e0b8e9519015bb62c60b9935a234cd367a1926a

ReactCommon/cxxreact/ReactNativeVersion.h

@@ -0,0 +1,24 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @generated by scripts/bump-oss-version.js
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <string_view>
+
+namespace facebook::react {
+
+constexpr struct {
+  int32_t Major = 0;
+  int32_t Minor = 0;
+  int32_t Patch = 0;
+  std::string_view Prerelease = "";
+} ReactNativeVersion;
+
+} // namespace facebook::react

scripts/bump-oss-version.js

@@ -84,6 +84,19 @@ fs.writeFileSync(
   'utf-8',
 );
 
+fs.writeFileSync(
+  'ReactCommon/cxxreact/ReactNativeVersion.h',
+  cat('scripts/versiontemplates/ReactNativeVersion.h.template')
+    .replace('${major}', major)
+    .replace('${minor}', minor)
+    .replace('${patch}', patch)
+    .replace(
+      '${prerelease}',
+      prerelease !== undefined ? `"${prerelease}"` : '""',
+    ),
+  'utf-8',
+);
+
 fs.writeFileSync(
   'Libraries/Core/ReactNativeVersion.js',
   cat('scripts/versiontemplates/ReactNativeVersion.js.template')

scripts/versiontemplates/ReactNativeVersion.h.template

@@ -0,0 +1,24 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @generated by scripts/bump-oss-version.js
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <string_view>
+
+namespace facebook::react {
+
+constexpr struct {
+  int32_t Major = ${major};
+  int32_t Minor = ${minor};
+  int32_t Patch = ${patch};
+  std::string_view Prerelease = ${prerelease};
+} ReactNativeVersion;
+
+} // namespace facebook::react