Update the OAuth2 handler to log error_description and error_uri when receiving an error

[kevinchalet]

#495 (comment)

FYI: the OIDC handler already does that: https://github.com/aspnet/Security/blob/dev/src/Microsoft.AspNet.Authentication.OpenIdConnect/OpenIdConnectHandler.cs#L382-L383

[brentschmaltz]

As long as the handler is sure the message is for itself this is fine, otherwise handlers will get in each others face. I have seen handlers where the param 'f' => failure.

[kevinchalet]

@brentschmaltz no risk: unlike the OIDC middleware (though it may change in the future: #455), the OAuth2 base middleware only listens on its own callback path, so unless you use the same one for multiple handlers, you shouldn't see any issue 👍

[HaoK]

620622f