Add LoginMode property in OktaMvcOptions

[laura-rodriguez]

Fixes #77

This property is only available on ASP.NET since ASP.NET Core already has a workaround: okta/samples-aspnetcore#27.

[OkGoDoIt]

I would elaborate here, maybe something like "LoginMode controls the login redirect behavior of the middleware"

[OkGoDoIt]

I would elaborate here, maybe something like "Controls the login behavior to redirect to internal or Okta-hosted login"

[OkGoDoIt]

So can this LoginMode property be set in the normal Web.config way too? Have you tested to make sure the enum is parsed properly? Maybe the docs need to be updated to list this as well?

[laura-rodriguez]

@OkGoDoIt Yes, you can set this property in the Web.Config as in this example:https://stackoverflow.com/questions/8148622/get-enum-values-from-web-config-at-run-time.
I don't think we need to test if this is parsed correctly since that's not the responsibility of the middleware.
Docs definitely need to be updated, but I wanted to hear the team's thoughts first.

[OkGoDoIt]

I would personally prefer to update the method summary in the second location I commented on above. And are you absolutely certain the web config is parsed correctly for the enum? The link you posted makes it look like you have to do it manually, but I don’t see any code on our end to handle that.

[laura-rodriguez]

Yeah, we don't have any code to handle that. The way to do that in this SDK is via Configuration object.

[OkGoDoIt]

Looks good, thanks for the updates