Summary:
This matches the behavior on iOS, there was no way before to change the cursor color per input, it was only possible to change it globally via the theme. Ideally cursor color and selection color would be 2 different props but I think this is better than what we have (and matches iOS).
Sadly there is no api to change it pragmatically (only possible via xml) so this uses reflection and can easily break so it is wrapped in a try catch to avoid crashes. I think it is better to just silently fail in this case. Definetly not super happy about the solution but I think it's worth adding since it is possible to do it natively using xml so it would suck not to be able to do it in RN.
**Test plan**
Tested that the cursor has the same color as before the change when not setting the prop and that it gets the selectionColor color when set.
Closes https://github.com/facebook/react-native/pull/12280
Differential Revision: D4571858
Pulled By: astreet
fbshipit-source-id: 7dca2db33a0a4eecb6115b45155549b1265ffbed
ae57b25134