[native] c++ interface to kill app on iOS and Android

Summary:
context: ENG-2158

This code will not generate crash reports, but simply exit the app.

It uses the same killing methods as already used react-native-exit-app but it's adapted to use this on c++ level and wrapped inside our logic.

Probably in the future, we can remove react-native-exit-app dependency and use this function exposed via CommCoreModule.

Test Plan:

1. Expose terminate function via CommCoreModule and pin to eg. dev tools inside profile tab.
2. Build this for both iOS and Android, check if it exits the app without any additional errors.
3. Check if the crash report wasn't generated.
4. Test on both physical devices.

Reviewers: marcin, jon, atul, tomek

Reviewed By: marcin, atul, tomek

Subscribers: ashoat, tomek, atul, abosh

Differential Revision: https://phab.comm.dev/D5618