Getting "page" within resolveComponent

[james-em]

PR open: #1864

Hi,

I would like to have a way to get the current request page in the resolveComponent callback.

Some context

Internally, the router gets setPage called and this function calls our resolveComponent, however it limits the object to the component property only.

export type PageResolver = (name: string) => Component
export interface Page<SharedProps extends PageProps = PageProps> {
  component: string
  props: PageProps...
   ...
}

protected setPage(page: Page, ...): Promise<void> {
    return Promise.resolve(this.resolveComponent(page.component)) <-- limitation here
}

It would be great if instead we could get the full page object in the resolveComponent function.

Motivation

I would like to pass the layout to render from my backend using props. Exemple

def index
  render :inertia, props: { layout: "MainLayout" }
end

const createApp = (initialPage) => createInertiaApp({
  page: initialPage,
  resolve: async (name) => {
    const component = await getComponent(routes[`./routes/${name}.svelte`]);
    return {
      default: component.default,
      layout: await getLayout(initialPage, component) <-- Motivation here. Only have access to the very first page from first page load
    }
  },
  setup({el, App, props}) {
    // Called only when isSSR is false
    new App({target: el, props})
  },
});

I'm willing to submit the required PR, however this would be a breaking change unless it's passed as a second parameter