Make Jest transform @react-native-community packages by default (#24294)

Summary:
Currently, `react-native` Jest preset will not automatically transpile extracted Lean Core modules (all under `react-native-community` org), so maintainers will likely need to update their docs on how to do that (it's a common pain in RN testing story).

We can make it easier for users and maintainers by adding RNC modules to the `transformIgnorePatterns` whitelist we have in Jest preset. Some of them are not necessary to transpile, but I'd say it's a small sacrifice to make (having first test run possibly slower) for having less friction around migrating to extracted modules.

[General] [Added] - make Jest transform react-native-community/ packages by default
Pull Request resolved: facebook/react-native#24294

Differential Revision: D14748962

Pulled By: cpojer

fbshipit-source-id: 36300ee021f03b8c13275a6e0cf28d988ee5beba

Author: thymikee

jest-preset.js

@@ -29,7 +29,7 @@ module.exports = {
     ),
   },
   transformIgnorePatterns: [
-    'node_modules/(?!(jest-)?react-native|react-clone-referenced-element)',
+    'node_modules/(?!(jest-)?react-native|@react-native-community|react-clone-referenced-element)',
   ],
   setupFiles: [require.resolve('./jest/setup.js')],
   testEnvironment: 'node',