feat: add support for react-native.config.ts

[szymonrybczak]

Summary:

Closes #2253

Test Plan:

1. Clone the repository and do all the required steps from the Contributing guide
2. Create react-native.config.ts with some config.
3. Run this command:

node /path/to/react-native-cli/packages/cli/build/bin.js config

4. Changes applied inside react-native.config.ts should be visible inside command's output.

Checklist

• Documentation is up to date to reflect these changes.
• Follows commit message convention described in CONTRIBUTING.md

[szymonrybczak]

I think we should export Config type through @react-native-community/cli so users could use it inside a config file:

import {Config} from '@react-native-community/cli';

const config: Config = {
  commands: [
    {
      name: 'hello  ',
      func: () => {
        console.log('hello');
      },
    },
  ],
};

export default config;

Right now it's exported through cli-types so users cannot import it directly from react-native.config.ts

[thymikee]

Let's add an e2e test that verifies a TS file is read

[szymonrybczak]

Let's add an e2e test that verifies a TS file is read

Tests landed ✅ might giving review again?