Add @react-native/metro-config package (#36502)

Summary:
Changelog:
[General][Added] - Add `react-native/metro-config` package

Pull Request resolved: https://github.com/facebook/react-native/pull/36502

## Context

### React Native Metro config → React Native repo (https://github.com/facebook/react-native/pull/36502)

We (the React Native team) are aiming to relocate the default Metro config for React Native out of `react-native-community/cli-plugin-metro` and **into the React Native repo + app template** as a new `react-native/metro-config` package.

This is the first (and minimum viable) phase we can ship to separate the release process of Metro from RN CLI in order to reduce coupling and iterate faster for our users.

**See full motivation, design, and test plan here: https://github.com/facebook/react-native/pull/36502**

## Changes

- This PR adds the new `react-native/metro-config` package, reproduces all static values previously defined in RN CLI. The values which remain in RN CLI are dynamic values derived from CLI options passed by the user.

{F906910591}

Reviewed By: cortinico

Differential Revision: D44099692

fbshipit-source-id: 672a67e19d866ac2c64fc84983b5d82c604918c6

packages/metro-config/index.js

@@ -0,0 +1,86 @@
+/**
+ * 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
+ * @noformat
+ */
+
+/*:: import type {ConfigT} from 'metro-config'; */
+
+const {getDefaultConfig: getBaseConfig, mergeConfig} = require('metro-config');
+
+const INTERNAL_CALLSITES_REGEX = new RegExp(
+  [
+    '/Libraries/Renderer/implementations/.+\\.js$',
+    '/Libraries/BatchedBridge/MessageQueue\\.js$',
+    '/Libraries/YellowBox/.+\\.js$',
+    '/Libraries/LogBox/.+\\.js$',
+    '/Libraries/Core/Timers/.+\\.js$',
+    '/Libraries/WebSocket/.+\\.js$',
+    '/Libraries/vendor/.+\\.js$',
+    '/node_modules/react-devtools-core/.+\\.js$',
+    '/node_modules/react-refresh/.+\\.js$',
+    '/node_modules/scheduler/.+\\.js$',
+    '/node_modules/event-target-shim/.+\\.js$',
+    '/node_modules/invariant/.+\\.js$',
+    '/node_modules/react-native/index.js$',
+    '/metro-runtime/.+\\.js$',
+    '^\\[native code\\]$',
+  ].join('|'),
+);
+
+/**
+ * Get the base Metro configuration for a React Native project.
+ */
+function getDefaultConfig(
+  projectRoot /*: string */
+) /*: ConfigT */ {
+  const config = {
+    resolver: {
+      resolverMainFields: ['react-native', 'browser', 'main'],
+      platforms: ['android', 'ios'],
+      unstable_conditionNames: ['import', 'require', 'react-native'],
+    },
+    serializer: {
+      getPolyfills: () => require('@react-native/js-polyfills')(),
+    },
+    server: {
+      port: Number(process.env.RCT_METRO_PORT) || 8081,
+    },
+    symbolicator: {
+      customizeFrame: (frame /*: $ReadOnly<{file: ?string, ...}>*/) => {
+        const collapse = Boolean(
+          frame.file && INTERNAL_CALLSITES_REGEX.test(frame.file),
+        );
+        return {collapse};
+      },
+    },
+    transformer: {
+      allowOptionalDependencies: true,
+      assetRegistryPath: 'react-native/Libraries/Image/AssetRegistry',
+      asyncRequireModulePath: require.resolve(
+        'metro-runtime/src/modules/asyncRequire',
+      ),
+      babelTransformerPath: require.resolve(
+        'metro-react-native-babel-transformer',
+      ),
+      getTransformOptions: async () => ({
+        transform: {
+          experimentalImportSupport: false,
+          inlineRequires: true,
+        },
+      }),
+    },
+    watchFolders: [],
+  };
+
+  return mergeConfig(
+    getBaseConfig.getDefaultValues(projectRoot),
+    config,
+  );
+}
+
+module.exports = {getDefaultConfig};

packages/metro-config/package.json

@@ -0,0 +1,16 @@
+{
+  "name": "@react-native/metro-config",
+  "version": "0.72.0",
+  "description": "Metro configuration for React Native.",
+  "repository": {
+    "type": "git",
+    "url": "git@github.com:facebook/react-native.git",
+    "directory": "packages/metro-config"
+  },
+  "license": "MIT",
+  "exports": "./index.js",
+  "dependencies": {
+    "@react-native/js-polyfills": "^0.72.1",
+    "metro-config": "0.75.1"
+  }
+}