Summary:
Related #23674, in that PR, we imported background timer support, but it's not sufficient, I think the reason that works is because it enable the `Background Modes` and do some background tasks, for the users who don't enable it, timer would pause immediately before goes into background.
To fix it, we can mark a background task when goes into background, it can keep app active for minutes, try best to support timing when in background.
cc. cpojer .
## Changelog
[iOS] [Fixed] - Timing: Fixes timer when app get into background
Pull Request resolved: https://github.com/facebook/react-native/pull/24649
Differential Revision: D15554451
Pulled By: cpojer
fbshipit-source-id: a33f7afe6b63d1a4fefcb7098459aee0c09145da
zhongwuzw
338298417f