Create a `DeferredSingleton` class that implements...

# kodein

[salomonbrys]

Create a DeferredSingleton class that implements NoArgBinding<Deferred<T>>, which uses builder.onProviderReady to directly start the work (just like EagerSingletonBinding does), work that it would put on a channel. Then, on its getInstance method, return a Deffered<T> that reads the value from the channel.