[change] Explicitly forward props and introduce unstable_{ariaSet,dataSet}

Rather than filtering props, they are explicitly forwarded in each component.
This makes it easier to see exactly which props are being forwarded to host
components by each React Native component. Two new props - `unstable_ariaSet`
and `unstable_dataSet` - are introduced to avoid iterating over props to find
`aria` and `data` props.

The `accessibilityValue` prop is also implemented.

packages/docs/src/components/View/View.stories.js

@@ -3,12 +3,12 @@ import PropTypes, { any, bool, func, object, oneOf, string } from 'prop-types';
 const ofProps = () => {};
 
 ofProps.propTypes = {
-  /* test */
   accessibilityLabel: PropTypes.string,
   accessibilityLiveRegion: oneOf(['assertive', 'none', 'polite']),
   accessibilityRelationship: object,
   accessibilityRole: string,
   accessibilityState: object,
+  accessibilityValue: object,
   accessible: bool,
   children: any,
   forwardedRef: any,

packages/docs/src/guides/accessibility.stories.mdx

@@ -89,6 +89,10 @@ assistive technologies of a `role` value change.
 
 ...
 
+### accessibilityValue: ?object
+
+...
+
 ### accessible
 
 When `true`, indicates that the view is an accessibility element. When a view