UserInputs are unable to be mapped to the OpenTAP Session that triggered it.

I need to be able to distinguish which OpenTAP Session triggered a given UserInput in the case where I'm using multiple OpenTAP Sessions in parallel.

Perhaps each Session should have a user input handler able to be set, e.g:

using (Session.Create(SessionOptions.OverlayComponentSettings))
{
    UserInput.SetInterface(UserInputHandler);
}

So UserInput is no longer a "global" thing, but a Session thing.