feat(theme): memoize createStyleProp

[Federkun]

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Short description of what this resolves:

Apparently StyleConsumerService's createStyleProp is quite slow. Memoize it is not a silver bullet, but give you a chance to not generate those styles on each rerender by providing props to your styled component with a stable identity.

My problem was a screen that had to re-render every 1s, which contained 15/20 buttons. On an iOS tablet, I usually drop to 2/3 fps. With this patch, given that all the props of the button have a stable identity (onPress in particular), I can maintain 60 fps.