ViewStateProps does not support a deck with multiple views

[ebbishop]

From the deck.gl docs:

When using multiple views, the viewState is a map from each view id to its respective view state object. See example.

(Note: The example linked above in the quoted docs shows initializing the deck's viewState incorrectly. I'm confirming this with deck.gl folks.)

Currently, the viewState property of DeckProps only accepts an object of type ViewStateProps. It should also accept an object that is a map from the various view ids to each view's own view state.