Set up a React example

steps to open the vue example
1. pnpm i
2. npm run dev:vue3-firestore

we need to add a new folder called `dev-react-firestore` which looks and works the same as `dev:vue3-firestore`

the magnetar instance is instantiated with `PluginVue3` and `PluginFirestore`, but the react one can use `PluginSimpleStore` and `PluginFirestore`. The rest of the syntax can be the exact same.