Add pnpm workspaces and improve Nuxt example

[wobsoriano]

Hey all! It's been a long time since my last PR here. I noticed we have a new repo for playgrounds, which is great since the main repo was starting to get crowded with playgrounds. Love it.

I'm opening a PR here to add an initial working example with pnpm workspaces. I've simplified the Nuxt playground by taking advantage of the built-in web Request and Response helpers:

export function NuxtAuthHandler(authOptions: AuthConfig) {
  return eventHandler(async (event) => {
    const request = toWebRequest(event) // h3 event to standard Request

    const url = new URL(request.url)
    const action = url.pathname
      .slice(authOptions.basePath!.length + 1)
      .split('/')[0] as AuthAction

    if (isAuthAction(action) && !url.pathname.startsWith(authOptions.basePath + '/')) {
      return
    }

    return await Auth(request, authOptions) // Nuxt now accepts a Response as a return value!
  })
}

I did not touch the gatsby example - don't really have experience with it.

[wobsoriano]

This is the 19k line change that can be ignored :p