Extract File Removal Functionality into New Method

[sweep-ai[bot]]

This PR addresses issue #26 by making the ios.rb script more modular. Specifically, it extracts the functionality that removes files from the existing colocated file group that are not present in the colocated_files array into a new method called remove_nonexistent_files.

The remove_nonexistent_files method takes two parameters: existing_group and colocated_files. This change makes the code easier to read and maintain, as each method now has a single, clear responsibility.

Please review and let me know if any changes are needed.

Fixes #26.

To checkout this PR branch, run the following command in your terminal:

git checkout sweep/feature/extract-file-removal