[Blazor] Adds an authentication library for Blazor webassembly (#18851)

* Adds a Microsoft.AspNetCore.Components.WebAssembly.Authentication
  library for performing authentication in Blazor webassembly.
* Includes a default implementation that supports OIDC capable IdPs
  using oidc-client.js
* Includes multiple primitives to deal with authentication flows and
  supports acquiring access tokens to call APIs.
  * RemoteAuthenticatorView is responsible for handling authentication
    operations at the user interface level.
  * RemoteAuthenticatorService is responsible for handling the lower
    level authentication details by using JavaScript interop to interact
    with the underlying javascript library implementing the auth protocol.
  * SignOutSessionStateManager handles CSRF protection for the logout
    path.
  * IAccessTokenProvider handles provisioning access tokens to call APIs.