Navigation-less screens

[Tiagoperes]

Not every server driven screen on every project will need navigation. Adding the whole structure of a navigator on a screen that doesn't need it is not great.

Provide a way for starting a Server Driven Screen without a navigator.

Suggestion:

StandaloneScreen(request: Request)
StandaloneScreen(url: String)

These screens won't have a View scope, which might require some adaptations on the code.