Dimensions and PixelRatio API

Do we want to support React Native's `Dimensions` and `PixelRatio`? Or discourage their use?

I propose supporting them, and adding injection systems for `react-sketchapp` to use global screen dimensions and pixel ratio values, but to later have an opt-out console warning layer to discourage their use and push for using `useWindowDimensions` instead, as dimensions should not be used as static values.

The main use-case for this would be aliasing `react-sketchapp`/`react-figma` to `@react-platform/native` and keeping things somewhat working. While aliasing will be discouraged by this project, it's a nice way to get a quick proof-of-concept running before refactoring a codebase to import common primitives.