Add RedirectToLogin configured login path (#35988)

Author: guardrex

aspnetcore/blazor/security/includes/redirecttologin-component.md

@@ -7,4 +7,29 @@ The `RedirectToLogin` component (`RedirectToLogin.razor`):
 
 Inspect the `RedirectToLogin` component in [reference source](https://github.com/dotnet/aspnetcore/tree/main/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp). The location of the component changed over time, so use GitHub search tools to locate the component.
 
+The login path can be customized by the app (<xref:Microsoft.AspNetCore.Components.WebAssembly.Authentication.RemoteAuthenticationApplicationPathsOptions.LogInPath%2A?displayProperty=nameWithType>, [framework defaults (`dotnet/aspnetcore` reference source)](https://github.com/dotnet/aspnetcore/blob/main/src/Components/WebAssembly/WebAssembly.Authentication/src/RemoteAuthenticationDefaults.cs)). The project template's `RedirectToLogin` component uses the default login path of `authentication/login`. 
+
 [!INCLUDE[](~/includes/aspnetcore-repo-ref-source-links.md)]
+
+If an app [customizes the login path](xref:blazor/security/webassembly/additional-scenarios#customize-app-routes), take either of the following approaches:
+
+* Match the path in the hard-coded string in the `RedirectToLogin` component.
+* Inject <xref:Microsoft.AspNetCore.Builder.RemoteAuthenticationOptions> to obtain the configured value. For example, take this approach when you customize the path with <xref:Microsoft.Extensions.DependencyInjection.WebAssemblyAuthenticationServiceCollectionExtensions.AddApiAuthorization%2A>.
+  Add the following directives at the top of the `RedirectToLogin` component:
+
+  ```razor
+  @using Microsoft.Extensions.Options
+  @inject IOptionsSnapshot<RemoteAuthenticationOptions<ApiAuthorizationProviderOptions>> RemoteOptions
+  ```
+
+  Modify the component's redirect in the `OnInitialized` method:
+
+  ```diff
+  - Navigation.NavigateToLogin("authentication/login");
+  + Navigation.NavigateToLogin(RemoteOptions.Get(Options.DefaultName)
+  +     .AuthenticationPaths.LogInPath);
+  ```
+
+  > [!NOTE]
+  > If other paths differ from the project template's paths or [framework's default paths](https://github.com/dotnet/aspnetcore/blob/main/src/Components/WebAssembly/WebAssembly.Authentication/src/RemoteAuthenticationDefaults.cs), they should managed in the same fashion.
+