Better Image API Parity with React Native

_I am..._

| -------------------------------------------------------------------------------------------------
| Requesting a new feature
| -------------------------------------------------------------------------------------------------

**Proposal/Feature-request:**

Improve the Image API parity with React Native by adding some of the static methods and extra props like `blurRadius`.

The main API method that would be useful is `Image.getSize()` to make getting image aspect ratios easier, for better use with the `useWindowDimensions` API. It's possible methods like `onLayout` could be implemented with the efforts in #472 too.

Implementation details:

- https://github.com/sketch-hq/sketch-reference-files/blob/master/files/123/images/pages/BE059DA8-F958-4C4A-A294-4FFB0713F90C.json#L100-L101
- https://developer.sketch.com/reference/api/#imagedata – (but probably not much use as won't work in Node.js/cross-platform mode)

Start with the existing Image API and review the React Native reference linked in the issue, along with the work in #472. Establish which static methods and props are in scope, prioritizing Image.getSize(), then verify the resulting API supports image aspect-ratio use with useWindowDimensions.

Written by the indexing model from the issue text.