[Dashboard] AspNetCore 3.0+ authorization policy support via extensions

[dasiths]

The current DashboardOptions constructor sets the LocalRequestsOnlyAuthorizationFilter as a default filter. When you setup your Hangfire Dashboard using the new endpoints pattern and set an authorization policy it still goes ahead and uses the default anyway. To circumvent it we need to pass an empty list to Authorization as shown below.

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers()
                    .RequireAuthorization();
                endpoints.MapHangfireDashboard("/dashboard/hangfire", new DashboardOptions()
                    {
                        // We need to pass an empty list or Hangfire will use a local authorization filter
                        Authorization = new List<IDashboardAuthorizationFilter>()
                    })
                    .RequireAuthorization("hangfire-specific-auth-scheme");
            });

The new extension method introduced in this PR supports passing an authorization policy name and removes the LocalRequestsOnlyAuthorizationFilter from the default if no DashboardOptions instance has been passed.

[dasiths]

How can I get this reviewed?

[leonio]

Perhaps this can just be Authorization = Enumerable.Empty<IDashboardAuthorizationFilter>()

[dasiths]

Thanks for the review @leonio. It doesn't make a whole lot of difference for readability or performance IMO. Can we let this go as is?

[leonio]

I don't have rights sorry, however this MR was very helpful for an issue I was resolving. FWIW hope it makes it through a full review.

[dasiths]

@odinserj any feedback on this?

[odinserj]

Thanks for your work and patience! Will merge this pull request and release changes with 1.7.24.