Upgrade the React Native generator to use React Native Web

**Description**

I would like to upgrade the React Native generator to use [Next + Expo](https://github.com/vercel/next.js/tree/canary/examples/with-expo-typescript) or [Next + React Native Web](https://github.com/vercel/next.js/tree/canary/examples/with-react-native-web).

The we could

* use Next also for the native app generator
* share most of the code between the web and the native Next generators, as we've done in the past for the react and the react native generator
* remove the React generators that aren't using Next