Summary:
Part of Lean Core #23313
Removes `SnapshotViewIOS` from the public RN interface.
I think there's a wider discussion to be had here about whether `RCTTest` should be part of the public distribution or at least whether this should be split into a separate utils package. It's mainly used by the RNTester app. It seems to be little known about but there are [some references to it online](https://blog.callstack.io/testing-your-react-native-apps-abfe41903dfd).
[iOS] [Removed] - `SnapshotViewIOS` is no longer publicly exported from RN
Pull Request resolved: https://github.com/facebook/react-native/pull/23497
Differential Revision: D14123280
Pulled By: cpojer
fbshipit-source-id: badaf6cb5d2195268f0f8b429fc11d6525747708
James Munro