Support @page Directive

[FlorianRappl]

The @page directive is used to automatically add pages to the router. Internally, this just adds the [PageAttribute] to the generated class.

Most likely, we could do some "magic" and introduce an auto inclusion of these pages. Potentially, it makes sense to trigger this via piral-blazor (explicitly), such that it could be turned off - if not desired.

export function setup(api) {
  api.defineBlazorReferences([...], {
    includePages: true, //set to false or omit to not auto discover
  });
}

[FlorianRappl]

This was brought in by @DanteDeRuwe! Thanks!