Added userInterfaceStyle prop to ActionSheetmanager to override user interface style for iOS 13 (#26401)

Summary:
Support to override actionsheet and share interface style to match your app. For example, when your app has it's own theming you want to match the stying on actionsheet and the share menu.

## Changelog

[iOS] [Added] - Added userInterfaceStyle for ActionSheetIOS and Share to override user interface style on IOS 13
Pull Request resolved: https://github.com/facebook/react-native/pull/26401

Test Plan:
Set dark style
![dark](https://user-images.githubusercontent.com/30040390/64685321-12a53080-d487-11e9-8846-f2ef89e114a2.jpg)
Set light style
![light](https://user-images.githubusercontent.com/30040390/64685322-12a53080-d487-11e9-9dfd-1e07b9fe0ce2.jpg)

Differential Revision: D17314080

Pulled By: hramos

fbshipit-source-id: f84278ca99ba20347d17e27295f661d6690fa68c