Add configurable token storage type for the Blazor WASM OIDC Authentication

[karmegams02]

Summary

Add OIDC token storage option for Blazor WebAssembly

Description

This PR adds a configurable option for where Blazor WebAssembly OIDC authentication state and tokens are stored in the browser.

Previously, OIDC authentication state was stored in sessionStorage, which is scoped to a single browser tab or window. As a result, users opening the same Blazor WebAssembly application in another tab or window were required to authenticate again, causing a poor user experience and repeated token requests.

This change introduces RemoteAuthenticationTokenStorage, allowing applications to choose between:

• SessionStorage

  • Default behavior.
  • Stores authentication state in window.sessionStorage.
  • Cleared when the tab or window is closed.
  • Not shared across tabs or windows.

• LocalStorage

  • Stores authentication state in window.localStorage.
  • Shared across tabs and windows for the same origin.
  • Persists across browser sessions.

The default remains SessionStorage to preserve existing behavior and avoid introducing a breaking change.

Changes included

• Added RemoteAuthenticationTokenStorage enum with:

  • SessionStorage
  • LocalStorage

• Added OidcProviderOptions.TokenStorage.

• Updated the WebAssembly authentication TypeScript interop to configure the oidc-client userStore using WebStorageStateStore.

• Added support for resolving token storage values from serialized configuration.

• Added public API entries for the new enum and option.

• Added unit tests for:

  • Default TokenStorage value.
  • Setting TokenStorage.
  • JSON serialization and deserialization.
  • Case-insensitive enum deserialization.
  • Invalid token storage values.
  • Missing token storage configuration.

• Added E2E coverage validating that:

  • TokenStorage = LocalStorage stores OIDC user state in localStorage.
  • Default/session storage behavior stores OIDC user state in sessionStorage.
  • The selected storage option is displayed by the test app.

Usage example

builder.Services.AddOidcAuthentication(options =>
{
    options.ProviderOptions.Authority = $"{builder.HostEnvironment.BaseAddress}oidc";
    options.ProviderOptions.ClientId = "s6BhdRkqt3";
    options.ProviderOptions.ResponseType = "code";
    options.ProviderOptions.TokenStorage = RemoteAuthenticationTokenStorage.LocalStorage;
});

Fixes #40757

[dotnet-policy-service]

Thanks for your PR, @karmegams02. Someone from the team will get assigned to your PR shortly and we'll get it reviewed.