Move functions defined in the main to the lib (dragoon/komodo!47)

## Description

Those functions in the main could be useful later as they are operations that an external user might actually want to do directly (instead of just rewriting the functions in the main).

## List of changes
- Create a dump function (to be be used by both dump_blocks and generate_powers as they write to disk)
- Created a fs mod for actions related to writing on disk
- moved functions into their relevant module (though some might be up to discussion, as noted in some commits)
- Use anyhow to be able to return Result from functions with multiple error types (since before they just threw errors in the main)

## Additional notes

Should I include the example that I was working on (ie writing blocks of files recursively), which was the thing that prompted me to actually move the functions from the main to the lib (as I noticed I was rewriting what was in the main to be able to do that) ?