Use a module request for asyncRequireModulePath so Metro's transform cache is shareable across checkouts

@react-native/metro-config set asyncRequireModulePath with require.resolve(),
which embeds the absolute path of the checkout in Metro's global transform
cache key. Two checkouts of the same project (git worktrees, CI workspaces)
never shared a transform cache entry. Add a react-native/async-require
secondary entry point, like react-native/asset-registry, and point the config
at it: a module request that resolves from any module in the project, hoisted
or not, because react-native is the app's direct dependency and depends on
metro-runtime itself.

Author: janicduplessis

packages/eslint-plugin-react-native/no-deep-imports.js

@@ -201,6 +201,7 @@ module.exports = {
 
       return (
         source.value === 'react-native/asset-registry' ||
+        source.value === 'react-native/async-require' ||
         source.value === 'react-native/react-private-interface' ||
         source.value === 'react-native/setup-env' ||
         source.value === 'react-native/unstable-internals-do-not-use'

packages/metro-config/src/index.flow.js

@@ -85,8 +85,7 @@ export function getDefaultConfig(projectRoot: string): ConfigT {
     transformer: {
       allowOptionalDependencies: true,
       assetRegistryPath: 'react-native/asset-registry',
-      asyncRequireModulePath:
-        require.resolve('metro-runtime/src/modules/asyncRequire'),
+      asyncRequireModulePath: 'react-native/async-require',
       babelTransformerPath:
         require.resolve('@react-native/metro-babel-transformer'),
       getTransformOptions: async () => ({

packages/react-native/package.json

@@ -49,6 +49,10 @@
       "types": null,
       "default": "./src/asset-registry.js"
     },
+    "./async-require": {
+      "types": null,
+      "default": "./src/async-require.js"
+    },
     "./react-private-interface": {
       "types": null,
       "default": "./src/react-private-interface.js"

packages/react-native/src/async-require.js

@@ -0,0 +1,27 @@
+/**
+ * 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.
+ *
+ * @flow strict-local
+ * @format
+ */
+
+'use strict';
+
+// ----------------------------------------------------------------------------
+// react-native/async-require
+//
+// This is an untyped secondary entry point intended to be referenced from
+// Metro's `transformer.asyncRequireModulePath` config option. Metro inlines
+// it into every module that uses `import()`, so it must be a module request
+// that resolves from any module in the project.
+//
+// Apps/libraries should not import this module; use `import()` instead.
+// ----------------------------------------------------------------------------
+
+const asyncRequire = require('metro-runtime/src/modules/asyncRequire');
+
+// eslint-disable-next-line @react-native/monorepo/no-commonjs-exports
+module.exports = asyncRequire;