Support parameterized FeatureToggles

[spshenychnyy-mechanicadvisor]

This library seem to be a standard for today's feature toggles in .NET world and I was surprised to find out it's missing parameterized features (e.g. I want to enable certain feature for some customers and disable for others). At least I couldn't find a way to easily implement that even with extensibility features. It would look weird to pass customerId in featureToggle constructor...

What would be nice to have is interface like

public interface IFeatureToggle<TArg>
{
    bool IsEnabled(TArg @for);
}