Use WebPack to build and serve the Web version of the example

In the example app, we support React Native Web using the Metro bundler with the metro.config.web.js configuration to create a bundled JS file to consume it from the index.html. This is not ideal for two reasons:

1. We are only creating a bundle that can be used directly at production, so we don't have a way to handle everything related to web development (assets, code splitting, CSS/styling, etc.).
2. We don't have a real development server, we just use a static server to serve the bundled JS on the index.html

Known issues

The main reason we started with a static server was that the example project is a workspace on a mono repo, so we need to find a way to consume react-native-spotlight-tour from another workspace and be able to replace all references to react-native imports with react-native-web. For iOS and Android, we use rnx-kit to solve this problem. But the web structure is different and rnx-kit doesn't seem to work as expected.