Remove iOS folder (pytorch#143398)

This folder is a tutorial that is not packaged in PyTorch that's an example of how to use the now deprecated Lite Interpreter

People should be using Executorch instead and there's already good documentation on it all over our tutorials and main homepage

Testing to see what breaks in CI

Pull Request resolved: pytorch#143398
Approved by: https://github.com/albanD

Author: msaroufim