Summary:
Currently the react native framework doesn't handle the accessibility state changes of the focused item that happen not upon double tapping. Screen reader doesn't get notified when the state of the focused item changes in the background.
To fix this problem, post a layout change notification for every state changes on iOS.
On Android, send a click event whenever state "checked", "selected" or "disabled" changes. In the case that such states changes upon user's clicking, the duplicated click event will be skipped by Talkback.
## Changelog:
[General][Fixed] - Announce accessibility state changes happening in the background
Pull Request resolved: https://github.com/facebook/react-native/pull/26624
Test Plan: Add a nested checkbox example which state changes after a delay in the AccessibilityExample.
Differential Revision: D17903205
Pulled By: cpojer
fbshipit-source-id: 9245ee0b79936cf11b408b52d45c59ba3415b9f9
baa66f63d8