What is equivalent to `MapSpaFallbackRoute` for ASP.NET Core 3.0 endpoints? : <p>In ASP.NET Core 2.x I used standard routes registation <code>Configure</code> method of <code>Startup</code> class to <strong>register fallback route</strong> for SPA application using <code>MapSpaFallbackRoute</code> extension method from <code>Microsoft.AspNetCore.SpaServices.Extensions</code> Nuget package:</p>

<pre class="lang-cs prettyprint-override"><code>public void Configure(IApplicationBuilder app)
{
    // ...
    app.UseMvc(routes =&gt;
    {
        routes.MapRoute(
            name: "default",
            template: "{controller=Home}/{action=Index}/{id?}");
        routes.MapSpaFallbackRoute(
            name: "spa-fallback",
            defaults: new { controller = "Home", action = "Index" });
    });
}
</code></pre>

<p>I cannot find similar extension method when using ASP.NET Core 3.0 recommended <code>UseEndpoints</code> extension method for endpoints registration.</p>
