…d by ajax method cause use agent CORS error.

Suggest enhancement
(1) in [AuthorizeForScopes] to provide a return url extract from ajax custom header for user agent to return to after the challenge is satisfied.
(2) in OpenIdConnentHandler,  after the redirect url for Identity Provider is calculated, for ajax request, the handler will return a 401 with this redirect url in the header location.

Added a test project to test modified AuthorizeForScopes Attribute to handle Ajax call. It depends on a locally built microsoft.aspnetcore.authentication.openidconnect dev nupkg within which associate change on ajax call redirection is handled differently (OpenIdConnectHandler need to be updated at Asp.net Core side).

…the lib project to test project.