Android textTransform style support (#20572)

Summary:
Issue https://github.com/facebook/react-native/issues/2088 (closed, but a bit pre-emptively imo, since Android support was skipped)

Related (merged) iOS PR https://github.com/facebook/react-native/pull/18387

Related documentation PR https://github.com/facebook/react-native-website/pull/500

The basic desire is to have a declarative mechanism to transform text content to uppercase or lowercase or titlecase ("capitalized").
Pull Request resolved: https://github.com/facebook/react-native/pull/20572

Differential Revision: D9311716

Pulled By: hramos

fbshipit-source-id: dfbb855117196958e7ae5e980700d31be07a448d

Libraries/Text/TextStylePropTypes.js

@@ -108,9 +108,6 @@ const TextStylePropTypes = {
    * @platform ios
    */
   textDecorationColor: ColorPropType,
-  /**
-   * @platform ios
-   */
   textTransform: ReactPropTypes.oneOf([
     'none' /*default*/,
     'capitalize',