[Blazor] Support AllowAnonymous on Blazor

[javiercn]

This prevents people from enabling authorization globally in a meaningful way for Blazor applications, since while you can apply [Authorize] globally through _Imports.Razor, that prevents you poking holes to allow individual access to unauthenticated pages.

The fixes can be:

• Check for [AllowAnonymous] attribute here to bypass checking the auth policy.
• Update the authorization package to handle AllowAnonymous within the authorization framework by making the policy succeed.
  • This second option is more involved but better in the end, since currently each individual framework (MVC, the authorization middleware and Blazor) all need to have code to handle this scenario.

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

Thanks for contacting us.
We're moving this issue to the Next sprint planning milestone for future evaluation / consideration. We will evaluate the request when we are planning the work for the next milestone. To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.