Securing Blazor Server

Blazor uses App.razor for routing. To enable securing Blazor, we need to add a couple of components in the app component.

We need to add a CascadingAuthenticationState, which will send the authentication state to all the components that are listening for it. We also need to change the route view to an AuthorizeRouteView, which can have different views depending on whether or not you are authenticated:

1. In the end, the App.razor component should look like this:

   <CascadingAuthenticationState>
       <Router AppAssembly="@typeof(App).Assembly" AdditionalAssemblies="new[] { typeof(Components.Pages.Index).Assembly}">
           <Found Context="routeData">
               <AuthorizeRouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)">
                   <Authorizing>
                       <p>Determining session state, please wait...</p>
                ...