Add '--remove-destination' option to cp command

[TGNThump]

Fixes #1762

[gemini-code-assist]

Code Review

This pull request adds the --remove-destination flag to a cp command within the copy_etc_to_state function. The goal is likely to make the copy operation more robust by ensuring destination files are removed before copying. While this is a good intention, my review highlights a potential portability issue. The --remove-destination flag is specific to GNU coreutils' cp and is not universally available, for instance in busybox. This could lead to failures if the code runs in a minimal environment. I've suggested that a more robust, long-term solution would be to replace the external command with a native Rust implementation for file copying, which would also resolve an existing TODO in the code.

[gursewak1997]

lgtm