Let Metro handle import/export instead of Babel (#1772)

* Let Metro handle import/export instead of Babel

* Keep using Babel for ESM->CJS in tests

metro.config.js

@@ -8,7 +8,17 @@ cfg.resolver.sourceExts = process.env.RN_SRC_EXT
 
 cfg.transformer.getTransformOptions = async () => ({
   transform: {
+    experimentalImportSupport: true,
     inlineRequires: true,
+    nonInlinedRequires: [
+      // We can remove this option and rely on the default after
+      // https://github.com/facebook/metro/pull/1126 is released.
+      'React',
+      'react',
+      'react/jsx-dev-runtime',
+      'react/jsx-runtime',
+      'react-native',
+    ],
   },
 })